Say "hi" to Moshi (Android Budapest meetup - January 2020)

JSON serialization is an everyday task for Android developers, but it's still not a trivial one. Long used solutions such as Gson have serious pain points, especially when using them with Kotlin. Could Moshi be our saviour when it comes to dealing with JSON on Android? We'll look at how to use it, what problems it solves, and how nicely it plays with our favourite JVM language.

Talk recording: https://www.youtube.com/watch?v=qadYVYc-8mc

Transcript

1. Say “hi”
   to
   zsmb.co zsmb13
   Márton Braun
   Moshi
   

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2. View Slide

3. Serialization
   @zsmb13
   

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4. JSON
   Serialization
   @zsmb13
   

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5. @zsmb13
   

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6. @zsmb13
   

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7. Gson
   github.com/google/gson
   @zsmb13
   

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8. Gson 101
   val burger: Burger = Gson().fromJson("{...}", Burger::class.java)
   val json: String = Gson().toJson(Burger())
   @zsmb13
   

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9. Gson 101
   val burger: Burger = Gson().fromJson("{...}", Burger::class.java)
   val json: String = Gson().toJson(Burger())
   @zsmb13
   

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10. Gson 101
    val burger: Burger = Gson().fromJson("{...}", Burger::class.java)
    val json: String = Gson().toJson(Burger())
    @zsmb13
    

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11. Gson 101
    val gson = Gson()
    val burger: Burger = Gson().fromJson("{...}", Burger::class.java)
    val json: String = Gson().toJson(Burger())
    @zsmb13
    

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12. Gson 101
    val gson = Gson()
    val burger: Burger = gson.fromJson("{...}", Burger::class.java)
    val json: String = gson.toJson(Burger())
    @zsmb13
    

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13. Gson
    val gson = Gson()
    val burger: Burger = gson.fromJson("{...}", Burger::class.java)
    val json: String = gson.toJson(Burger())
    101
    @zsmb13
    

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14. Gson
    val gson = Gson()
    : built-in types
    @zsmb13
    

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15. Gson
    val gson = Gson()
    gson.toJson(Date())
    : built-in types
    @zsmb13
    

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16. Gson
    val gson = Gson()
    gson.toJson(Date())
    "Jan 30, 2020 7:03:50 PM"
    : built-in types
    @zsmb13
    

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17. Gson
    val gson = Gson()
    gson.toJson(Date())
    "Jan 30, 2020 7:03:50 PM"
    gson.toJson(Calendar.getInstance())
    : built-in types
    @zsmb13
    

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18. Gson
    val gson = Gson()
    gson.toJson(Date())
    "Jan 30, 2020 7:03:50 PM"
    gson.toJson(Calendar.getInstance())
    {"year":2020,"month":0,"dayOfMonth":30,"hourOfDay":19,
    "minute":03,"second":50}
    : built-in types
    @zsmb13
    

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19. Gson
    val gson = Gson()
    gson.toJson(Date())
    "Jan 30, 2020 7:03:50 PM"
    gson.toJson(Calendar.getInstance())
    {"year":2020,"month":0,"dayOfMonth":30,"hourOfDay":19,
    "minute":03,"second":50}
    gson.toJson(Random())
    : built-in types
    @zsmb13
    

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20. Gson
    val gson = Gson()
    gson.toJson(Date())
    "Jan 30, 2020 7:03:50 PM"
    gson.toJson(Calendar.getInstance())
    {"year":2020,"month":0,"dayOfMonth":30,"hourOfDay":19,
    "minute":03,"second":50}
    gson.toJson(Random())
    {"seed":{"value":137564286790437},"nextNextGaussian":0.0,
    "haveNextNextGaussian":false}
    : built-in types
    @zsmb13
    

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21. Gson: field naming
    val gson = Gson()
    @zsmb13
    

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22. Gson: field naming
    val gson = GsonBuilder()
    .create()
    @zsmb13
    

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23. val gson = GsonBuilder()
    .setFieldNamingPolicy(
    FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
    .create()
    Gson: field naming
    @zsmb13
    

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24. val gson = GsonBuilder()
    .setFieldNamingPolicy(
    FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
    .create()
    Gson: field naming
    data class Burger(
    val name: String,
    val totalCost: Int,
    val salesPrice: Int
    )
    @zsmb13
    

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25. val gson = GsonBuilder()
    .setFieldNamingPolicy(
    FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES)
    .create()
    Gson: field naming
    data class Burger(
    val name: String,
    val totalCost: Int,
    val salesPrice: Int
    )
    gson.toJson(Burger("Classic", 10, 13))
    {"name":"Classic","total_cost":10,"sales_price":13}
    @zsmb13
    

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26. @SerializedName("name")
    @SerializedName("total_cost")
    @SerializedName("sales_price")
    Gson()
    Gson: field naming
    gson.toJson(Burger("Classic", 10, 13))
    {"name":"Classic","total_cost":10,"sales_price":13}
    data class Burger(
    val gson =
    val name: String,
    val totalCost: Int,
    )
    val salesPrice: Int
    @zsmb13
    

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27. Gson: missing data
    Gson()
    val gson =
    @zsmb13
    

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28. data class Burger(
    val name: String,
    val price: Int
    )
    Gson: missing data
    Gson()
    val gson =
    @zsmb13
    

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29. data class Burger(
    val name: String,
    val price: Int
    )
    Gson: missing data
    val burger = gson.fromJson("{\"name\": \"Cheeseburger\"}",
    Burger::class.java)
    Gson()
    val gson =
    @zsmb13
    

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30. data class Burger(
    val name: String,
    val price: Int
    )
    Gson: missing data
    val burger = gson.fromJson("{\"name\": \"Cheeseburger\"}",
    Burger::class.java)
    Burger(name=Cheeseburger, price=0)
    Gson()
    val gson =
    @zsmb13
    

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31. data class Burger(
    val name: String,
    val description: String
    )
    val gson = Gson()
    Gson: missing data
    val burger = gson.fromJson("{\"name\": \"Cheeseburger\"}",
    Burger::class.java)
    @zsmb13
    

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32. data class Burger(
    val name: String,
    val description: String
    )
    val gson = Gson()
    Gson: missing data
    val burger = gson.fromJson("{\"name\": \"Cheeseburger\"}",
    Burger::class.java)
    Burger(name=Cheeseburger, description=null)
    @zsmb13
    

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33. data class Burger(
    val name: String,
    val description: String = "One of our best burgers!"
    )
    val gson = Gson()
    Gson: missing data
    val burger = gson.fromJson("{\"name\": \"Cheeseburger\"}",
    Burger::class.java)
    @zsmb13
    

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34. data class Burger(
    val name: String,
    val description: String = "One of our best burgers!"
    )
    val gson = Gson()
    Gson: missing data
    val burger = gson.fromJson("{\"name\": \"Cheeseburger\"}",
    Burger::class.java)
    Burger(name=Cheeseburger, description=null)
    @zsmb13
    

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35. val gson = Gson()
    Gson: malformed data
    @zsmb13
    

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36. val gson = Gson()
    Gson: malformed data
    data class Burger(val name: String, val price: Int)
    data class Restaurant(val menu: List)
    @zsmb13
    

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37. val gson = Gson()
    Gson: malformed data
    data class Burger(val name: String, val price: Int)
    data class Restaurant(val menu: List)
    val json = """{
    "menu": [
    { "name": "Classic", "price": 10 },
    { "name": "Cheeseburger", "price": 13 },
    { "name": "Double", "price": "crocodile" }
    ]
    }"""
    @zsmb13
    

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38. val gson = Gson()
    Gson: malformed data
    data class Burger(val name: String, val price: Int)
    data class Restaurant(val menu: List)
    val json = """{
    "menu": [
    { "name": "Classic", "price": 10 },
    { "name": "Cheeseburger", "price": 13 },
    { "name": "Double", "price": "crocodile" }
    ]
    }"""
    @zsmb13
    

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39. val gson = Gson()
    Gson: malformed data
    data class Burger(val name: String, val price: Int)
    data class Restaurant(val menu: List)
    val json = """{
    "menu": [
    { "name": "Classic", "price": 10 },
    { "name": "Cheeseburger", "price": 13 },
    { "name": "Double", "price": "crocodile" }
    ]
    }"""
    val restaurant = gson.fromJson(json, Restaurant::class.java)
    @zsmb13
    

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40. Gson: malformed data
    val gson = Gson()
    data class Burger(val name: String, val price: Int)
    data class Restaurant(val menu: List)
    val json = """{
    "menu": [
    { "name": "Classic", "price": 10 },
    { "name": "Cheeseburger", "price": 13 },
    { "name": "Double", "price": "crocodile" }
    ]
    }"""
    val restaurant = gson.fromJson(json, Restaurant::class.java)
    Exception in thread "main"
    com.google.gson.JsonSyntaxException:
    java.lang.NumberFormatException:
    For input string: "crocodile"
    @zsmb13
    

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41. val gson = Gson()
    Gson: malformed data
    data class Burger(val name: String, val price: Int)
    data class Restaurant(val menu: List)
    val json = """{
    "menu": [
    { "name": "Classic", "price": 10 },
    { "name": "Cheeseburger", "price": 13 },
    { "name": "Double", "price": "" }
    ]
    }"""
    val restaurant = gson.fromJson(json, Restaurant::class.java)
    Exception in thread "main"
    com.google.gson.JsonSyntaxException:
    java.lang.NumberFormatException:
    For input string: ""
    @zsmb13
    

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42. Say “hi”
    to
    zsmb.co zsmb13
    Márton Braun
    Moshi
    

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43. Moshi
    github.com/square/moshi
    @zsmb13
    

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44. Okio
    github.com/square/okio
    Retrofit
    github.com/square/retrofit
    Moshi
    github.com/square/moshi
    OkHttp
    github.com/square/okhttp
    @zsmb13
    

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45. Moshi
    github.com/square/moshi
    @zsmb13
    

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46. Moshi 101
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    @zsmb13
    

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47. public JavaBurger(String name, int price) {
    this.name = name;
    this.price = price;
    }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public int getPrice() { return price; }
    public void setPrice(int price) { this.price = price; }
    Moshi 101
    }
    public class JavaBurger {
    private String name;
    private int price;
    @zsmb13
    

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48. // ...
    public JavaBurger(String name, int price) {
    this.name = name;
    this.price = price;
    }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public int getPrice() { return price; }
    public void setPrice(int price) { this.price = price; }
    Moshi 101
    }
    public class JavaBurger {
    private String name;
    private int price;
    @zsmb13
    

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49. // ...
    public JavaBurger(String name, int price) {
    this.name = name;
    this.price = price;
    }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public int getPrice() { return price; }
    public void setPrice(int price) { this.price = price; }
    Moshi 101
    val moshi = Moshi.Builder().build()
    }
    public class JavaBurger {
    private String name;
    private int price;
    @zsmb13
    

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50. // ...
    public JavaBurger(String name, int price) {
    this.name = name;
    this.price = price;
    }
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }
    public int getPrice() { return price; }
    public void setPrice(int price) { this.price = price; }
    Moshi 101
    val moshi = Moshi.Builder().build()
    val json = moshi.toJson(JavaBurger("Classic", 10))
    }
    public class JavaBurger {
    private String name;
    private int price;
    @zsmb13
    

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51. // ...
    Moshi 101
    val moshi = Moshi.Builder().build()
    val json = moshi.toJson(JavaBurger("Classic", 10))
    }
    public class JavaBurger {
    private String name;
    private int price;
    @zsmb13
    

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52. // ...
    Moshi 101
    val moshi = Moshi.Builder().build()
    val json = moshi.toJson(JavaBurger("Classic", 10))
    }
    public class JavaBurger {
    private String name;
    private int price;
    val burgerAdapter: JsonAdapter =
    moshi.adapter(JavaBurger::class.java)
    @zsmb13
    

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53. // ...
    Moshi 101
    val moshi = Moshi.Builder().build()
    }
    public class JavaBurger {
    private String name;
    private int price;
    val burgerAdapter: JsonAdapter =
    moshi.adapter(JavaBurger::class.java)
    val json = burgerAdapter.toJson(JavaBurger("Classic", 10))
    @zsmb13
    

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54. // ...
    Moshi 101
    val moshi = Moshi.Builder().build()
    }
    public class JavaBurger {
    private String name;
    private int price;
    val burgerAdapter: JsonAdapter =
    moshi.adapter(JavaBurger::class.java)
    val json = burgerAdapter.toJson(JavaBurger("Classic", 10))
    {"name":"Classic","price":10}
    @zsmb13
    

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55. // ...
    Moshi 101
    val moshi = Moshi.Builder().build()
    }
    public class JavaBurger {
    private String name;
    private int price;
    val burgerAdapter: JsonAdapter =
    moshi.adapter(JavaBurger::class.java)
    val json = burgerAdapter.toJson(JavaBurger("Classic", 10))
    {"name":"Classic","price":10}
    val burger = burgerAdapter.fromJson(json)
    @zsmb13
    

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56. Burger::class.java)
    val moshi = Moshi.Builder().build()
    (val : String, val : Int)
    val burgerAdapter: JsonAdapter =
    moshi.adapter(
    Burger
    class name price
    @zsmb13
    Moshi ft. Kotlin
    

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57. Burger::class.java)
    val moshi = Moshi.Builder().build()
    (val : String, val : Int)
    val burgerAdapter: JsonAdapter =
    moshi.adapter(
    Burger
    class name price
    @zsmb13
    Moshi ft. Kotlin
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Cannot serialize Kotlin type
    com.example.Burger. Reflective
    serialization of Kotlin classes
    without using kotlin-reflect has
    undefined and unexpected behavior.
    Please use KotlinJsonAdapter from
    the moshi-kotlin artifact or use
    code gen from the moshi-kotlin-
    codegen artifact.
    

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58. Moshi ft. Kotlin
    val moshi = Moshi.Builder().build()
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    @zsmb13
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Cannot serialize Kotlin type
    com.example.Burger. Reflective
    serialization of Kotlin classes
    without using kotlin-reflect has
    undefined and unexpected behavior.
    Please use KotlinJsonAdapter from
    the moshi-kotlin artifact or use
    code gen from the moshi-kotlin-
    codegen artifact.
    

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59. Moshi ft. Kotlin
    val moshi = Moshi.Builder().build()
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    @zsmb13
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Cannot serialize Kotlin type
    com.example.Burger. Reflective
    serialization of Kotlin classes
    without using kotlin-reflect has
    undefined and unexpected behavior.
    Please use KotlinJsonAdapter from
    the moshi-kotlin artifact or use
    code gen from the moshi-kotlin-
    codegen artifact.
    

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60. val moshi = Moshi.Builder().build()
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    @zsmb13
    Moshi ft. Kotlin
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Cannot serialize Kotlin type
    com.example.Burger. Reflective
    serialization of Kotlin classes
    without using kotlin-reflect has
    undefined and unexpected behavior.
    Please use KotlinJsonAdapter from
    the moshi-kotlin artifact or use
    code gen from the moshi-kotlin-
    codegen artifact.
    

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61. val moshi = Moshi.Builder().build()
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    @zsmb13
    Moshi: reflection
    

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62. val moshi = Moshi.Builder().build()
    Moshi: reflection
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    implementation "com.squareup.moshi:moshi-kotlin:$moshi_version"
    @zsmb13
    

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63. val moshi = Moshi.Builder()
    Moshi: reflection
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    .build()
    @zsmb13
    

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64. Moshi: reflection
    .add(KotlinJsonAdapterFactory())
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    .build()
    val moshi = Moshi.Builder()
    @zsmb13
    

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65. Moshi: reflection
    .add(KotlinJsonAdapterFactory())
    val burgerAdapter: JsonAdapter =
    moshi.adapter(Burger::class.java)
    class Burger(val name: String, val price: Int)
    val json = burgerAdapter.toJson(Burger("Classic", 10))
    val burger = burgerAdapter.fromJson(json)
    .build()
    val moshi = Moshi.Builder()
    @zsmb13
    

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66. Moshi: reflection
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    implementation "com.squareup.moshi:moshi-kotlin:$moshi_version"
    @zsmb13
    

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67. Moshi: reflection
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    implementation "com.squareup.moshi:moshi-kotlin:$moshi_version"
    @zsmb13
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Cannot serialize Kotlin type
    com.example.Burger. Reflective
    serialization of Kotlin classes
    without using kotlin-reflect has
    undefined and unexpected behavior.
    Please use KotlinJsonAdapter from
    the moshi-kotlin artifact or use
    code gen from the moshi-kotlin-
    codegen artifact.
    

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68. implementation moshi-kotlin:$moshi_version"
    "com.squareup.moshi:
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    @zsmb13
    Moshi: reflection
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Cannot serialize Kotlin type
    com.example.Burger. Reflective
    serialization of Kotlin classes
    without using kotlin-reflect has
    undefined and unexpected behavior.
    Please use KotlinJsonAdapter from
    the moshi-kotlin artifact or use
    code gen from the
    artifact.
    moshi-kotlin-
    codegen
    

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69. def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    kapt moshi-kotlin-codegen:$moshi_version"
    "com.squareup.moshi:
    @zsmb13
    Moshi: codegen
    

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70. dependencies {
    }
    Moshi: codegen
    apply plugin: 'kotlin'
    apply plugin: 'kotlin-kapt'
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
    @zsmb13
    

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71. Moshi: codegen
    class Burger(val name: String, val price: Int)
    @zsmb13
    

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72. @JsonClass(generateAdapter = true)
    class Burger(val name: String, val price: Int)
    @zsmb13
    Moshi: codegen
    

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73. @JsonClass(generateAdapter = true)
    class Burger(val name: String, val price: Int)
    val moshi = Moshi.Builder().build()
    val burgerAdapter = moshi.adapter(Burger::class.java)
    val json = burgerAdapter.toJson(Burger("Double", 18)))
    @zsmb13
    Moshi: codegen
    

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74. dependencies {
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    implementation "com.squareup.moshi:moshi-kotlin:$moshi_version"
    kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
    }
    apply plugin: 'kotlin'
    apply plugin: 'kotlin-kapt'
    val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()
    @zsmb13
    Moshi: mixed use
    

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75. Moshi: mixed use
    dependencies {
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    implementation "com.squareup.moshi:moshi-kotlin:$moshi_version"
    kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
    }
    apply plugin: 'kotlin'
    apply plugin: 'kotlin-kapt'
    val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()
    @zsmb13
    

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76. dependencies {
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    implementation "com.squareup.moshi:moshi-kotlin:$moshi_version"
    kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
    }
    apply plugin: 'kotlin'
    apply plugin: 'kotlin-kapt'
    val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()
    @zsmb13
    Moshi: mixed use
    

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77. class CustomBurgerAdapter {
    TODO("Implement deserialization")
    @ToJson
    fun toJson(writer: JsonWriter, value: Burger?) {
    TODO("Implement serialization")
    }
    }
    @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    }
    @zsmb13
    Moshi: custom adapters
    

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78. @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    }
    @zsmb13
    Moshi: custom adapters
    

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79. Moshi: custom adapters
    @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    var name: String? = null
    var price: Int? = null
    }
    @zsmb13
    

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80. Moshi: custom adapters
    @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    reader.endObject()
    }
    @zsmb13
    

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81. Moshi: custom adapters
    @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    }
    reader.endObject()
    }
    @zsmb13
    

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82. Moshi: custom adapters
    @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.nextName()) {
    "name" -> name = reader.nextString()
    "price" -> price = reader.nextInt()
    else -> reader.skipValue()
    }
    }
    reader.endObject()
    }
    @zsmb13
    

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83. @FromJson
    fun fromJson(reader: JsonReader): Burger? {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.nextName()) {
    "name" -> name = reader.nextString()
    "price" -> price = reader.nextInt()
    else -> reader.skipValue()
    }
    }
    reader.endObject()
    return Burger(name!!, price!!)
    }
    @zsmb13
    : custom adapters
    Moshi
    

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84. class BurgerJsonAdapter(
    moshi: Moshi
    ) : JsonAdapter() {
    override fun toString(): String = buildString(28) {
    append("GeneratedJsonAdapter(").append("Burger").append(')')
    }
    private val options: JsonReader.Options =
    JsonReader.Options.of("name", "price")
    private val stringAdapter: JsonAdapter =
    moshi.adapter(String::class.java, emptySet(), "name")
    private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    return Burger(
    name = name ?:
    throw Util.missingProperty("name", "name", reader),
    price = price ?:
    throw Util.missingProperty("price", "price", reader)
    )
    }
    override fun toJson(writer: JsonWriter, value: Burger?) {
    if (value == null) {
    throw NullPointerException(
    "value was null! Wrap in .nullSafe() to write nullable values.")
    }
    writer.beginObject()
    writer.name("name")
    stringAdapter.toJson(writer, value.name)
    writer.name("price")
    intAdapter.toJson(writer, value.price)
    writer.endObject()
    }
    }
    @zsmb13
    Moshi’s generated adapter
    

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85. class BurgerJsonAdapter(
    moshi: Moshi
    ) : JsonAdapter() {
    override fun toString(): String = buildString(28) {
    append("GeneratedJsonAdapter(").append("Burger").append(')')
    }
    private val options: JsonReader.Options =
    JsonReader.Options.of("name", "price")
    private val stringAdapter: JsonAdapter =
    moshi.adapter(String::class.java, emptySet(), "name")
    private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    Moshi’s generated adapter
    @zsmb13
    

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86. private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    Moshi’s generated adapter
    @zsmb13
    

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87. private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    Moshi’s generated adapter
    @zsmb13
    

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88. private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    Moshi’s generated adapter
    @zsmb13
    

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89. private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    Moshi’s generated adapter
    @zsmb13
    

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90. private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    Moshi’s generated adapter
    @zsmb13
    

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91. override fun toString(): String = buildString(28) {
    append("GeneratedJsonAdapter(").append("Burger").append(')')
    }
    private val options: JsonReader.Options =
    JsonReader.Options.of("name", "price")
    private val stringAdapter: JsonAdapter =
    moshi.adapter(String::class.java, emptySet(), "name")
    private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    Moshi’s generated adapter
    @zsmb13
    

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92. private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    Moshi’s generated adapter
    @zsmb13
    

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93. private val options: JsonReader.Options =
    JsonReader.Options.of("name", "price")
    private val stringAdapter: JsonAdapter =
    moshi.adapter(String::class.java, emptySet(), "name")
    private val intAdapter: JsonAdapter =
    moshi.adapter(Int::class.java, emptySet(), "price")
    override fun fromJson(reader: JsonReader): Burger {
    var name: String? = null
    var price: Int? = null
    reader.beginObject()
    while (reader.hasNext()) {
    when (reader.selectName(options)) {
    0 -> name = stringAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("name", "name", reader)
    1 -> price = intAdapter.fromJson(reader) ?:
    throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    Moshi’s generated adapter
    @zsmb13
    

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94. throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    return Burger(
    name = name ?:
    throw Util.missingProperty("name", "name", reader),
    price = price ?:
    throw Util.missingProperty("price", "price", reader)
    )
    }
    }
    Moshi’s generated adapter
    @zsmb13
    

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95. throw Util.unexpectedNull("price", "price", reader)
    -1 -> {
    reader.skipName()
    reader.skipValue()
    }
    }
    }
    reader.endObject()
    return Burger(
    name = name ?:
    throw Util.missingProperty("name", "name", reader),
    price = price ?:
    throw Util.missingProperty("price", "price", reader)
    )
    }
    }
    @zsmb13
    Moshi’s generated adapter
    

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96. val moshi = Moshi.Builder().build()
    val adapter: JsonAdapter =
    moshi.adapter(Date::class.java)
    @zsmb13
    Moshi: built-in types
    

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97. Moshi: built-in types
    val moshi = Moshi.Builder().build()
    val adapter: JsonAdapter =
    moshi.adapter(Date::class.java)
    Exception in thread "main"
    java.lang.IllegalArgumentException:
    Platform class java.util.Date
    requires explicit JsonAdapter to be
    registered
    @zsmb13
    

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98. Moshi: built-in types
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
    val moshi = Moshi.Builder().build()
    val adapter: JsonAdapter =
    moshi.adapter(Date::class.java)
    @zsmb13
    

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99. Moshi: built-in types
    def moshi_version = '1.9.2'
    implementation "com.squareup.moshi:moshi:$moshi_version"
    kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
    implementation "com.squareup.moshi:moshi-adapters:$moshi_version"
    val moshi = Moshi.Builder().build()
    val adapter: JsonAdapter =
    moshi.adapter(Date::class.java)
    @zsmb13
    

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100. val adapter: JsonAdapter =
     moshi.adapter(Date::class.java)
     def moshi_version = '1.9.2'
     implementation "com.squareup.moshi:moshi:$moshi_version"
     implementation "com.squareup.moshi:moshi-adapters:$moshi_version"
     kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
     .add(Date::class.java, Rfc3339DateJsonAdapter())
     .build()
     val moshi = Moshi.Builder()
     @zsmb13
     Moshi: built-in types
     

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101. val adapter: JsonAdapter =
     moshi.adapter(Date::class.java)
     def moshi_version = '1.9.2'
     implementation "com.squareup.moshi:moshi:$moshi_version"
     implementation "com.squareup.moshi:moshi-adapters:$moshi_version"
     kapt "com.squareup.moshi:moshi-kotlin-codegen:$moshi_version"
     .add(Date::class.java, Rfc3339DateJsonAdapter())
     2020-01-30T19:03:50.250Z
     .build()
     val moshi = Moshi.Builder()
     @zsmb13
     Moshi: built-in types
     

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102. @zsmb13
     Moshi: field naming
     

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103. @JsonClass(generateAdapter = true)
     data class Burger(
     @Json(name = "name")
     val name: String,
     @Json(name = "total_cost")
     val totalCost: Int,
     @Json(name = "sales_price")
     val salesPrice: Int
     )
     @zsmb13
     Moshi: field naming
     

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104. @JsonClass(generateAdapter = true)
     data class Burger(
     @Json(name = "name")
     val name: String,
     @Json(name = "total_cost")
     val totalCost: Int,
     @Json(name = "sales_price")
     val salesPrice: Int
     )
     moshi.adapter(Burger::class.java)
     .toJson(Burger("Classic", 10, 13))
     @zsmb13
     Moshi: field naming
     

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105. @JsonClass(generateAdapter = true)
     data class Burger(
     @Json(name = "name")
     val name: String,
     @Json(name = "total_cost")
     val totalCost: Int,
     @Json(name = "sales_price")
     val salesPrice: Int
     )
     moshi.adapter(Burger::class.java)
     .toJson(Burger("Classic", 10, 13))
     {"name":"Classic","total_cost":10,"sales_price":13}
     @zsmb13
     Moshi: field naming
     

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106. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val total_cost: Int,
     val sales_price: Int
     )
     moshi.adapter(Burger::class.java)
     .toJson(Burger("Classic", 10, 13))
     {"name":"Classic","total_cost":10,"sales_price":13}
     @zsmb13
     Moshi: field naming
     

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107. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val price: Int
     )
     @zsmb13
     Moshi: missing data
     

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108. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val price: Int
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     @zsmb13
     

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109. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val price: Int
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Required value 'price' missing at $
     @zsmb13
     

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110. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val description: String
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     @zsmb13
     

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111. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val description: String
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Required value 'description' missing at $
     @zsmb13
     

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112. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val description: String?
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     @zsmb13
     

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113. @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val description: String?
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     Burger(name=Cheeseburger, description=null)
     @zsmb13
     

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114. Burger(name=Cheeseburger, description=null)
     @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val description: String = "One of our best burgers!"
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     @zsmb13
     

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115. Burger(name=Cheeseburger, description=null)
     @JsonClass(generateAdapter = true)
     data class Burger(
     val name: String,
     val description: String = "One of our best burgers!"
     )
     Moshi: missing data
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\"}"
     )
     Burger(name=Cheeseburger, description=One of our best burgers!)
     @zsmb13
     

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116. Shameless plug
     https://zsmb.co/primaries-matter-a-discussion-of-constructors/
     @zsmb13
     

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117. val moshi = Moshi.Builder()
     Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     .build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\", \"price\": 13}"
     )
     @zsmb13
     

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118. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     .add(...)
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\", \"price\": 13}"
     )
     .build()
     val moshi = Moshi.Builder()
     @zsmb13
     

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119. val moshi = Moshi.Builder()
     Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     .build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     val burger = burgerAdapter.fromJson(
     "{\"name\": \"Cheeseburger\", \"price\": 13}"
     )
     @zsmb13
     

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120. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     JsonAdapter
     @zsmb13
     

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121. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     @zsmb13
     

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122. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int?)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.toJson(Burger("Cancelled", null))
     @zsmb13
     

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123. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int?)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.toJson(Burger("Cancelled", null))
     {"name":"Cancelled"}
     @zsmb13
     

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124. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int?)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     .serializeNulls()
     burgerAdapter.toJson(Burger("Cancelled", null))
     {"name":"Cancelled","price":null}
     @zsmb13
     

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125. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.toJson(null)
     @zsmb13
     

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126. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.toJson(null)
     null
     @zsmb13
     

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127. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     .nullSafe()
     burgerAdapter.toJson(null)
     null
     @zsmb13
     

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128. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     .nonNull()
     burgerAdapter.toJson(null)
     @zsmb13
     

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129. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     .nonNull()
     burgerAdapter.toJson(null)
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Unexpected null at $
     @zsmb13
     

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130. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     @zsmb13
     

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131. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.fromJson(
     "{\"name\":\"Cheeseburger\",\"price\": 13}"
     )
     @zsmb13
     

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132. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.fromJson(
     "{\"name\":\"Cheeseburger\",\"price\": 13}"
     )
     Burger(name=Cheeseburger, price=13)
     @zsmb13
     

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133. Moshi: customization options
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     burgerAdapter.fromJson(
     "{\"name\":\"Cheeseburger\",\"price\": 13,\"rating\":4.2}"
     )
     Burger(name=Cheeseburger, price=13)
     @zsmb13
     

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134. @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     .failOnUnknown()
     burgerAdapter.fromJson(
     "{\"name\":\"Cheeseburger\",\"price\": 13,\"rating\":4.2}"
     )
     Moshi: customization options
     @zsmb13
     

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135. @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     val moshi = Moshi.Builder().build()
     val burgerAdapter = moshi.adapter(Burger::class.java)
     .failOnUnknown()
     burgerAdapter.fromJson(
     "{\"name\":\"Cheeseburger\",\"price\": 13,\"rating\":4.2}"
     )
     Moshi: customization options
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Cannot skip unexpected NAME at $.rating
     @zsmb13
     

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136. Moshi: malformed data
     @zsmb13
     

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137. @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     @zsmb13
     Moshi: malformed data
     

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138. @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     val json = """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     @zsmb13
     Moshi: malformed data
     

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139. @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     val json = """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     val restaurant = adapter.fromJson(json, Restaurant::class.java)
     @zsmb13
     Moshi: malformed data
     

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140. Moshi: malformed data
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     val json = """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     val restaurant = adapter.fromJson(json, Restaurant::class.java)
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     @zsmb13
     

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141. val json =
     val restaurant = adapter.fromJson(json, Restaurant::class.java)
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     Moshi: malformed data
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     @zsmb13
     

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142. """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     @zsmb13
     

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143. Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     @zsmb13
     

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144. Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     @zsmb13
     

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145. Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     @zsmb13
     

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146. Moshi: malformed data
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     val json =
     val restaurant = adapter.fromJson(json, Restaurant::class.java)
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     @zsmb13
     

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147. Moshi: malformed data
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     val json =
     val restaurant = adapter.fromJson(json, Restaurant::class.java)
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "crocodile" }
     ]
     }"""
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was crocodile at
     path $.menu[2].price
     Exception in thread "main"
     com.google.gson.JsonSyntaxException:
     java.lang.NumberFormatException:
     For input string: "crocodile"
     @zsmb13
     

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148. Moshi: malformed data
     @JsonClass(generateAdapter = true)
     data class Burger(val name: String, val price: Int)
     @JsonClass(generateAdapter = true)
     data class Restaurant(val menu: List)
     val json =
     val restaurant = adapter.fromJson(json, Restaurant::class.java)
     """{
     "menu": [
     { "name": "Classic", "price": 10 },
     { "name": "Cheeseburger", "price": 13 },
     { "name": "Double", "price": "" }
     ]
     }"""
     @zsmb13
     Exception in thread "main"
     com.squareup.moshi.JsonDataException:
     Expected an int but was at
     path $.menu[2].price
     Exception in thread "main"
     com.google.gson.JsonSyntaxException:
     java.lang.NumberFormatException:
     For input string: ""
     

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149. Retrofit.Builder()
     .baseUrl("...")
     .addConverterFactory(MoshiConverterFactory.create())
     .build()
     def retrofit_version = '2.7.1'
     implementation "com.squareup.retrofit2:retrofit:$retrofit_version"
     implementation "com.squareup.retrofit2:converter-moshi:$retrofit_version"
     @zsmb13
     Moshi: Retrofit integration
     

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150. Retrofit.Builder()
     .baseUrl("...")
     .addConverterFactory(MoshiConverterFactory.create())
     .build()
     def retrofit_version = '2.7.1'
     implementation "com.squareup.retrofit2:retrofit:$retrofit_version"
     implementation "com.squareup.retrofit2:converter-moshi:$retrofit_version"
     val moshi = Moshi.Builder()
     .add(KotlinJsonAdapterFactory())
     .add(...)
     .build()
     @zsmb13
     Moshi: Retrofit integration
     

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151. Retrofit.Builder()
     .baseUrl("...")
     .addConverterFactory(MoshiConverterFactory.create(
     .build()
     def retrofit_version = '2.7.1'
     implementation "com.squareup.retrofit2:retrofit:$retrofit_version"
     implementation "com.squareup.retrofit2:converter-moshi:$retrofit_version"
     val moshi = Moshi.Builder()
     .add(KotlinJsonAdapterFactory())
     .add(...)
     .build()
     @zsmb13
     Moshi: Retrofit integration
     ))
     moshi
     

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152. More Moshi…
     •Other built-in adapters
     •Intermediate objects while parsing
     •Annotated types
     •Parsing arrays and other generic types
     •A lot more under-the-hood details!
     @zsmb13
     

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153. Resources
     •A Few Ok Libraries (Jake Wharton, Square) –
     Droidcon Montreal 2015
     • https://www.youtube.com/watch?v=WvyScM_S88c
     •Upgrading to Moshi (Eric Cochran, Pinterest) -
     droidcon NYC 2017
     • https://www.youtube.com/watch?v=xHFs7cccnXU
     •JSON Explained (Jesse Wilson, Square) –
     Chicago Roboto 2019
     • https://www.youtube.com/watch?v=1PwdqkKDCSo
     @zsmb13
     

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154. Resources
     •Moshi, another JSON Processor (Jesse Wilson)
     • https://developer.squareup.com/blog/moshi-another-json-processor/
     •Exploring Moshi’s codegen (Zac Sweers)
     • https://www.zacsweers.dev/exploring-moshis-kotlin-code-gen/
     •Reflection Machines (Jesse Wilson)
     • https://publicobject.com/2016/03/24/reflection-machines/
     •Advanced JSON parsing techniques using Moshi and
     Kotlin (Christophe Beyls)
     • https://medium.com/@BladeCoder/advanced-json-parsing-techniques-
     using-moshi-and-kotlin-daf56a7b963d
     @zsmb13
     

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155. zsmb.co/talks
     zsmb13
     Márton Braun
     › Reflection or codegen
     › Kotlin friendly
     › Really fast
     › Great failure modes
     Say “hi” to Moshi
     

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