How Java and Kotlin work together @ca.kt#2

Transcript

1. How Java and Kotlin work together Taku Semba CyberAgent.Inc
2. About Me Taku Semba TakuSemba @takusemba AbemaTV.Inc
3. Call Kotlin from Java
4. //kotlin class User { var name: String = "" }
5. //java User user = new User(); user.setName("taku"); user.getName(); // taku //kotlin class User { var name: String = "" }
6. //java User user = new User(); user.setName("taku"); user.getName(); // taku //kotlin class User { val name: String = "taku" }
7. //java User user = new User(); user.getName(); // taku //kotlin class User { val name: String = "taku" }
8. //kotlin class User { val name: String = "taku" fun getName(): String { return "my name is $name" } } //java User user = new User(); user.getName(); // taku
9. //kotlin class User { val name: String = "taku" fun getName(): String { return "my name is $name" } } //java User user = new User(); user.getName(); // taku
10. //kotlin class User { @JvmField val name: String = "taku" fun getName(): String { return "my name is $name" } } //java User user = new User(); user.getName(); // taku
11. //kotlin class User { @JvmField val name: String = "taku" fun getName(): String { return "my name is $name" } } //java User user = new User(); String name = user.name; // taku user.getName(); // my name is taku
12. //kotlin class User { @JvmField val name: String = "taku" fun getName(name: String = "semba"): String { return "my name is $name" } } //java User user = new User(); String name = user.name; // taku user.getName(); // my name is taku
13. //kotlin class User { @JvmField val name: String = "taku" @JvmOverloads fun getName(name: String = "semba"): String { return "my name is $name" } } //java User user = new User(); String name = user.name; // taku user.getName(); // my name is semba
14. //kotlin class User { companion object { fun callName(name: String): String { return "hi, $name" } } //java User.Companion.callName("taku");
15. //kotlin class User { companion object { @JvmStatic fun callName(name: String): String { return "hi, $name" } } //java User.Companion.callName("taku");
16. //kotlin class User { companion object { @JvmStatic fun callName(name: String): String { return "hi, $name" } } //java User.callName("taku");
17. //kotlin class User { companion object { val name: String = "taku" @JvmStatic fun callName(name: String): String { return "hi, $name" } } //java User.callName("taku"); String name = User.Companion.getName();
18. //kotlin class User { companion object { const val name: String = "taku" @JvmStatic fun callName(name: String): String { return "hi, $name" } } //java User.callName("taku"); String name = User.Companion.getName();
19. //kotlin class User { companion object { const val name: String = "taku" @JvmStatic fun callName(name: String): String { return "hi, $name" } } //java User.callName("taku"); String name = User.name;
20. //prefExt.kt fun SharedPreferences.getUserId(): String { return getString("userId", null) ?: throw IllegalStateException(“user id does not exist“) }
21. //MainActivity.kt val sp = getPreferences(Context.MODE_PRIVATE) val userId = sp.getUserId() //prefExt.kt fun SharedPreferences.getUserId(): String { return getString("userId", null) ?: throw IllegalStateException(“user id does not exist“) }
22. //prefExt.kt fun SharedPreferences.getUserId(): String { return getString("userId", null) ?: throw IllegalStateException(“user id does not exist“) }
23. //prefExt.kt fun SharedPreferences.getUserId(): String { return getString("userId", null) ?: throw IllegalStateException(“user id does not exist“) } //MainActivity.java SharedPreferences sp = getPreferences(Context.MODE_PRIVATE); String userId = PrefExtKt.getUserId(sp);
24. //MainActivity.java SharedPreferences sp = getPreferences(Context.MODE_PRIVATE); String userId = PrefExtKt.getUserId(sp); //prefExt.kt @file:JvmName("PrefUtil") fun SharedPreferences.getUserId(): String { return getString("userId", null) ?: throw IllegalStateException(“user id does not exist“) }
25. //MainActivity.java SharedPreferences sp = getPreferences(Context.MODE_PRIVATE); String userId = PrefUtil.getUserId(sp); //prefExt.kt @file:JvmName("PrefUtil") fun SharedPreferences.getUserId(): String { return getString("userId", null) ?: throw IllegalStateException(“user id does not exist“) }
26. //prefExt.kt fun SharedPreferences.edit(func: (SharedPreferences.Editor) -> Unit) { val editor = edit() func(editor) editor.apply() }
27. //prefExt.kt fun SharedPreferences.edit(func: (SharedPreferences.Editor) -> Unit) { val editor = edit() func(editor) editor.apply() } //MainActivity.kt val sp = getPreferences(Context.MODE_PRIVATE) sp.edit { editor -> editor.putString("key", "value") }
28. //prefExt.kt fun SharedPreferences.edit(func: (SharedPreferences.Editor) -> Unit) { val editor = edit() func(editor) editor.apply() } //MainActivity.kt val sp = getPreferences(Context.MODE_PRIVATE) sp.edit { it.putString("key", "value") }
29. //MainActivity.kt val sp = getPreferences(Context.MODE_PRIVATE) sp.edit { it.putString("key", "value") } //prefExt.kt fun SharedPreferences.edit(func: SharedPreferences.Editor.() -> Unit) { val editor = edit() editor.func() editor.apply() }
30. //MainActivity.kt val sp = getPreferences(Context.MODE_PRIVATE) sp.edit { putString("key", "value") } //prefExt.kt fun SharedPreferences.edit(func: SharedPreferences.Editor.() -> Unit) { val editor = edit() editor.func() editor.apply() }
31. //prefExt.kt fun SharedPreferences.edit(func: SharedPreferences.Editor.() -> Unit) { val editor = edit() editor.func() editor.apply() }
32. //prefExt.kt fun SharedPreferences.edit(func: SharedPreferences.Editor.() -> Unit) { val editor = edit() editor.func() editor.apply() } //MainActivity.java PrefExtKt.edit(sp, editor -> { editor.putString("key", "value"); return Unit.INSTANCE; });
33. //prefExt.kt inline fun SharedPreferences.edit(func: SharedPreferences.Editor.() -> Unit) { val editor = edit() editor.func() editor.apply() } //MainActivity.java PrefExtKt.edit(sp, editor -> { editor.putString("key", "value"); return Unit.INSTANCE; });
34. //prefExt.kt
35. //prefExt.kt inline fun <reified T> SharedPreferences.get(key: String, default: T): T { if (default is String) return getString(key, default) as T if (default is Int) return getInt(key, default) as T if (default is Float) return getFloat(key, default) as T if (default is Long) return getLong(key, default) as T if (default is Boolean) return getBoolean(key, default) as T throw IllegalStateException("failed to get value") }
36. //prefExt.kt inline fun <reified T> SharedPreferences.get(key: String, default: T): T { if (default is String) return getString(key, default) as T if (default is Int) return getInt(key, default) as T if (default is Float) return getFloat(key, default) as T if (default is Long) return getLong(key, default) as T if (default is Boolean) return getBoolean(key, default) as T throw IllegalStateException("failed to get value") } //MainActivity.kt val sp = getPreferences(Context.MODE_PRIVATE) val a= sp.get("key", 0L) // return as Long val b = sp.get("key", "my default") // return as String
37. //prefExt.kt inline fun <reified T> SharedPreferences.get(key: String, default: T): T { if (default is String) return getString(key, default) as T if (default is Int) return getInt(key, default) as T if (default is Float) return getFloat(key, default) as T if (default is Long) return getLong(key, default) as T if (default is Boolean) return getBoolean(key, default) as T throw IllegalStateException("failed to get value") }
38. //prefExt.kt inline fun <reified T> SharedPreferences.get(key: String, default: T): T { if (default is String) return getString(key, default) as T if (default is Int) return getInt(key, default) as T if (default is Float) return getFloat(key, default) as T if (default is Long) return getLong(key, default) as T if (default is Boolean) return getBoolean(key, default) as T throw IllegalStateException("failed to get value") } //MainActivity.java SharedPreferences sp = getPreferences(Context.MODE_PRIVATE); PrefExtKt.get(sp, "key", 0L);
39. //prefExt.kt inline fun <reified T> SharedPreferences.get(key: String, default: T): T { if (default is String) return getString(key, default) as T if (default is Int) return getInt(key, default) as T if (default is Float) return getFloat(key, default) as T if (default is Long) return getLong(key, default) as T if (default is Boolean) return getBoolean(key, default) as T throw IllegalStateException("failed to get value") } //MainActivity.java SharedPreferences sp = getPreferences(Context.MODE_PRIVATE); PrefExtKt.get(sp, "key", 0L); // get() has a private access in PrefExtKt
40. How Java and Kotlin work together https://github.com/takusemba https://twitter.com/takusemba