Kotlin Android Extensions and Anko

Presentation done at meetup group KotlinTLV

Transcript

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2. Together.
   Learn.
   

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3. Agenda
   • Kotlin Android Extensions
   • Anko
   • Coroutines
   

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4. Android Kotlin Extensions
   

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5. Kotlin Android Extensions (KAE)
   • Gradle Plugin
   • Replaces view injecting libraries
   • No more findViewsById()
   • Be careful
   

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6. KAE Use
   apply plugin: ‘kotlin-android-extensions'
   // Part of Kotlin IDEA Plugin so no extra dependencies
   

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7. KAE Use
   import kotlinx.android.synthetic.main.fragment_episodes.recyclerView
   android:id="@+id/recyclerView"
   android:layout_width="match_parent"
   android:layout_height="match_parent" />
   override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
   super.onViewCreated(view, savedInstanceState)
   recyclerView.setHasFixedSize(true)
   recyclerView.layoutManager = LinearLayoutManager(context)
   }
   

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8. KAE Magic?
   public View _$_findCachedViewById(int var1) {
   }
   private HashMap _$_findViewCache;
   if(this._$_findViewCache == null) {
   this._$_findViewCache = new HashMap();
   }
   View var2 = (View)this._$_findViewCache.get(Integer.valueOf(var1));
   if(var2 == null) {
   View var10000 = this.getView();
   if(var10000 == null) {
   return null;
   }
   var2 = var10000.findViewById(var1);
   this._$_findViewCache.put(Integer.valueOf(var1), var2);
   }
   return var2;
   

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9. KAE Decompilation
   public void onViewCreated(@Nullable View view, @Nullable Bundle savedInstanceState) {
   super.onViewCreated(view, savedInstanceState);
   ((RecyclerView)this._$_findCachedViewById(id.recyclerView)).setHasFixedSize(true);
   ((RecyclerView)this._$_findCachedViewById(id.recyclerView))
   .setLayoutManager((LayoutManager)(new LinearLayoutManager(this.getContext())));
   }
   override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
   super.onViewCreated(view, savedInstanceState)
   recyclerView.setHasFixedSize(true)
   recyclerView.layoutManager = LinearLayoutManager(context)
   }
   // $FF: synthetic method
   public void onDestroyView() {
   super.onDestroyView();
   this._$_clearFindViewByIdCache();
   }
   

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10. KAE ViewHolder
    class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    fun bind(item: Item, listener: (Item) -> Unit) = with(itemView) {
    date.text = simpleDateFormatter.format(item.pubDate)
    name.text = item.title
    Picasso.with(context)
    .load(item.image!!.href)
    .placeholder(ContextCompat.getDrawable(context, R.drawable.placeholder))
    .into(image)
    description.text = item.description
    duration.text = item.duration?.value ?: ""
    card.setOnClickListener { listener(item) }
    }
    }
    

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11. KAE ViewHolder Decompilation
    public final void bind(@NotNull Item item, @NotNull Function1 listener) {
    Intrinsics.checkParameterIsNotNull(item, "item");
    Intrinsics.checkParameterIsNotNull(listener, "listener");
    View var3 = this.itemView;
    ((TextView)var3.findViewById(id.date)).setText(…);
    ((TextView)var3.findViewById(id.name)).setText((CharSequence)item.getTitle());
    (….)
    ((CardView)var3.findViewById(id.card)).setOnClickListener(…);
    }
    

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12. KAE ViewHolder The Right Way™
    class ViewHolder(override val containerView: View?) : RecyclerView.ViewHolder(containerView), LayoutContainer {
    fun bind(item: Item, listener: (Item) -> Unit) = with(itemView) {
    date.text = simpleDateFormatter.format(item.pubDate)
    name.text = item.title
    Picasso.with(context)
    .load(item.image!!.href)
    .placeholder(ContextCompat.getDrawable(context, R.drawable.placeholder))
    .into(image)
    description.text = item.description
    duration.text = item.duration?.value ?: ""
    card.setOnClickListener { listener(item) }
    }
    }
    public interface LayoutContainer {
    public val containerView: View?
    }
    

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13. KAE ViewHolder The Right Way™
    public View _$_findCachedViewById(int var1) {
    if(this._$_findViewCache == null) {
    this._$_findViewCache = new HashMap();
    }
    View var2 = (View)this._$_findViewCache.get(Integer.valueOf(var1));
    if(var2 == null) {
    View var10000 = this.getContainerView();
    if(var10000 == null) {
    return null;
    }
    var2 = var10000.findViewById(var1);
    this._$_findViewCache.put(Integer.valueOf(var1), var2);
    }
    return var2;
    }
    private HashMap _$_findViewCache;
    

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14. KAE ViewHolder The Right Way™
    public final void bind(@NotNull Item item, @NotNull Function1 listener) {
    Intrinsics.checkParameterIsNotNull(item, "item");
    Intrinsics.checkParameterIsNotNull(listener, "listener");
    ((TextView)this._$_findCachedViewById(id.date)).setText(…);
    ((TextView)this._$_findCachedViewById(id.name)).setText((CharSequence)item.getTitle());
    (..)
    ((CardView)this._$_findCachedViewById(id.card)).setOnClickListener(…);
    }
    // Same for Custom Views!
    

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15. Anko
    

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16. Anko
    • Anko Commons
    • Anko Layouts
    • Anko SQLite
    • Anko Coroutines
    

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17. Anko Commons - Intents
    fun startActivity(context: Context) {
    val intent = Intent(context, MainActivity::class.java)
    intent.putExtra(EXTRA_STATE, "3")
    context.startActivity(intent)
    }
    fun startActivity(context: Context) {
    context.startActivity(EXTRA_STATE to 3)
    }
    fun startActivity(context: Context) = context.startActivity(EXTRA_STATE to 3)
    context.share("url to a new podcast!”)
    

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18. Anko Commons - Dialogs
    context.alert("Hi, I'm Roy", "Have you tried turning it off and on again?") {
    yesButton { context.toast("Oh…") }
    noButton {}
    }.show()
    

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19. Anko Commons - Logging
    class EpisodesPresenter(private val callback: WeakReference): AnkoLogger {
    fun someFunction(item: Item) {
    info("clicked on $item")
    warn("This is a warning")
    }
    }
    

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20. Anko Commons - Misc
    // colors
    0xff0000.opaque // non-transparent red
    0x99.gray.opaque // non-transparent #999999 gray
    // Dimensions
    val dip = dip(20) // 60
    val sp = sp(20) // 60
    val px2dip = px2dip(100) // 33.333332
    

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21. Anko Layouts - before
    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    return inflater!!.inflate(R.layout.fragment_episodes, container, false)
    }
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/viewSwitcher"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:inAnimation="@android:anim/fade_in"
    android:outAnimation="@android:anim/fade_out"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".fragment.EpisodesFragment">
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center" />
    
    

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22. Anko Layouts - after
    override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    return UI {
    verticalLayout {
    padding = dip(30)
    editText {
    hint = "Name"
    textSize = 24f
    }
    editText {
    hint = "Password"
    textSize = 24f
    }
    button("Login") {
    textSize = 26f
    }
    }
    }.view
    }
    

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23. Anko SQLite
    class DatabaseOpenHelper(ctx: Context) : ManagedSQLiteOpenHelper(ctx, "MyDatabase", null, 1) {
    companion object {
    private var instance: DatabaseOpenHelper? = null
    @Synchronized
    fun getInstance(ctx: Context): DatabaseOpenHelper {
    if (instance == null) {
    instance = DatabaseOpenHelper(ctx.applicationContext)
    }
    return instance!!
    }
    }
    override fun onCreate(db: SQLiteDatabase) {
    // Here you create tables
    db.createTable("Customer", false,
    "id" to INTEGER,
    "name" to TEXT,
    "photo" to BLOB)
    }
    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
    // Here you can upgrade tables, as usual
    db.dropTable("Customer", true)
    }
    }
    

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24. Anko Coroutines
    

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25. Anko Coroutines - before
    object GetRssFeedRequest {
    fun getFeed(callback: Callback) {
    val retrofit = RetrofitUtils.getRetrofit()
    val service = retrofit.create(RssFeedService::class.java)
    val feed = service.getFeed()
    feed.enqueue(callback)
    }
    }
    

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26. Anko Coroutines - before
    fun getFeed(): LiveData> {
    val data = MutableLiveData>()
    GetRssFeedRequest.getFeed(object : Callback { // retrofit
    override fun onResponse(call: Call?, response: Response?) {
    val rss = response?.body()
    if (rss != null) {
    data.value = Resource.success(rss)
    }
    }
    override fun onFailure(call: Call?, t: Throwable?) {
    Log.d(TAG, t?.localizedMessage)
    data.value = Resource.error()
    }
    })
    return data
    }
    

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27. Anko Coroutines - after
    object GetRssFeedRequest {
    fun getFeed(): Response? {
    val retrofit = RetrofitUtils.getRetrofit()
    val service = retrofit.create(RssFeedService::class.java)
    val feed = service.getFeed()
    return feed.execute()
    }
    }
    

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28. Anko Coroutines - after
    fun getFeed(): LiveData> {
    val data = MutableLiveData>()
    async(UI) {
    val deferred = bg { GetRssFeedRequest.getFeed() }
    val response = deferred.await()
    if (response != null) {
    if(response.isSuccessful) {
    data.value = Resource.success(response.body()!!)
    } else {
    data.value = Resource.error()
    }
    }
    }
    return data
    }
    

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29. Anko Coroutines - after & shorter
    fun getFeed(): LiveData> {
    val data = MutableLiveData>()
    async(UI) {
    val response: Response? = bg { GetRssFeedRequest.getFeed() }.await()
    data.value = if(response?.isSuccessful == true) Resource.success(response.body()!!) else Resource.error()
    }
    return data
    }
    

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30. Anko Coroutines - Activity
    override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    async(UI) {
    val deferred: Deferred?> = bg {
    GetRssFeedRequest.getFeed()
    }
    val response: Response? = deferred.await()
    if(response != null && response.isSuccessful) {
    manageRss(response.body())
    }
    }
    } Any Leak here?
    

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31. Anko Coroutines - Activity TRW
    override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    val ref = asReference()
    async(UI) {
    val deferred: Deferred?> = bg {
    GetRssFeedRequest.getFeed()
    }
    val response: Response? = deferred.await()
    if(response != null && response.isSuccessful) {
    ref().manageRss(response.body())
    }
    }
    }
    No leaks!
    

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32. Questions?
    

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33. Giveaways!
    

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34. 3 Jetbrains licenses
    

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35. Kotlin In Action
    val coupon45 = “KOTLINTLV”
    

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36. Thank you
    @galex
    

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