Potenciando el desarrollo Android con Kotlin

Esta charla fue dada en el marco. del Kotlin Everywhere Neuquén, un evento para difundir el uso de Kotlin en diferentes ambientes.

La charla trata sobre Android. KTX y de cómo las características únicas de Kotlin pueden potenciar el desarrollo de las aplicaciones Android.

Transcript

1. POTENCIANDO EL DESARROLLO ANDROID CON KOTLIN RICARDO MARKIEWICZ ANDROID ENGINEER AT SIMPLEX SOFTWARE
2. HABÍA UNA VEZ UN BUG db.beginTransaction(); try { // Save data } catch { // Error in between database transaction } finally { db.endTransaction(); }
3. HABÍA UNA VEZ UN BUG db.beginTransaction(); try { // Save data db.setTransactionSuccessful(); } catch { // Error in between database transaction } finally { db.endTransaction(); }
4. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
5. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
6. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
7. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
8. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
9. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
10. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
11. KOTLIN EXTENSIONS fun SQLiteDatabase.transaction(code: SQLiteDatabase.() -> Unit) { try { beginTransaction() code() setTransactionSuccessful() } catch (e: TransactionAbortException) { // Do nothing, just stop the transaction } finally { endTransaction() } }
12. HABÍA UNA VEZ UN BUG db.beginTransaction(); try { // Save data db.setTransactionSuccessful(); } catch { // Error in between database transaction } finally { db.endTransaction(); }
13. HABÍA UNA VEZ UN BUG db.transaction { // Save data }
14. EVITAR TAREAS REPETITIVAS ViewTreeObserver vto = view.getViewTreeObserver(); vto.addOnGlobalLayoutListener (new OnGlobalLayoutListener() { @Override public void onGlobalLayout() { view.getViewTreeObserver() .removeOnGlobalLayoutListener(this); int width = layout.getMeasuredWidth(); int height = layout.getMeasuredHeight(); } });
15. EVITAR TAREAS REPETITIVAS ViewTreeObserver vto = view.getViewTreeObserver(); vto.addOnGlobalLayoutListener (new OnGlobalLayoutListener() { @Override public void onGlobalLayout() { view.getViewTreeObserver() .removeOnGlobalLayoutListener(this); int width = layout.getMeasuredWidth(); int height = layout.getMeasuredHeight(); } });
16. EVITAR TAREAS REPETITIVAS inline fun View.waitForLayout(crossinline f: () -> Unit) { with(viewTreeObserver) { addOnGlobalLayoutListener( object : ViewTreeObserver.OnGlobalLayoutListener { override fun onGlobalLayout() { removeOnGlobalLayoutListener(this) f() } } ) } }
17. EVITAR TAREAS REPETITIVAS inline fun View.waitForLayout(crossinline f: () -> Unit) { with(viewTreeObserver) { addOnGlobalLayoutListener( object : ViewTreeObserver.OnGlobalLayoutListener { override fun onGlobalLayout() { removeOnGlobalLayoutListener(this) f() } } ) } }
18. EVITAR TAREAS REPETITIVAS inline fun View.waitForLayout(crossinline f: () -> Unit) { with(viewTreeObserver) { addOnGlobalLayoutListener( object : ViewTreeObserver.OnGlobalLayoutListener { override fun onGlobalLayout() { removeOnGlobalLayoutListener(this) f() } } ) } }
19. EVITAR TAREAS REPETITIVAS inline fun View.waitForLayout(crossinline f: () -> Unit) { with(viewTreeObserver) { addOnGlobalLayoutListener( object : ViewTreeObserver.OnGlobalLayoutListener { override fun onGlobalLayout() { removeOnGlobalLayoutListener(this) f() } } ) } }
20. EVITAR TAREAS REPETITIVAS inline fun View.waitForLayout(crossinline f: () -> Unit) { with(viewTreeObserver) { addOnGlobalLayoutListener( object : ViewTreeObserver.OnGlobalLayoutListener { override fun onGlobalLayout() { removeOnGlobalLayoutListener(this) f() } } ) } }
21. EVITAR TAREAS REPETITIVAS ViewTreeObserver vto = view.getViewTreeObserver(); vto.addOnGlobalLayoutListener (new OnGlobalLayoutListener() { @Override public void onGlobalLayout() { view.getViewTreeObserver() .removeOnGlobalLayoutListener(this); int width = view.getMeasuredWidth(); int height = view.getMeasuredHeight(); } });
22. EVITAR TAREAS REPETITIVAS view.waitForLayout { int width = view.getMeasuredWidth(); int height = view.getMeasuredHeight(); }
24. ANDROID KTX Android KTX is a set of Kotlin extensions that are included with Android Jetpack and other Android libraries. KTX extensions provide concise, idiomatic Kotlin to Jetpack, Android platform, and other APIs. https://developer.android.com/kotlin/ktx
25. SharedPreferences https://developer.android.com/kotlin/ktx sharedPreferences .edit() // create an Editor .putBoolean("key", value) .apply() // write to disk asynchronously
26. SharedPreferences https://developer.android.com/kotlin/ktx sharedPreferences.edit { putBoolean("key", value) }}
27. SharedPreferences https://developer.android.com/kotlin/ktx sharedPreferences.edit { putBoolean("key", value) putString("other", "some value") }}
28. USANDO KTX repositories { google() } dependencies { implementation 'androidx.core:core-ktx:1.0.1' } https://developer.android.com/kotlin/ktx
29. USANDO KTX • Fragment KTX - androidx.fragment:fragment-ktx:$version • Palette KTX - androidx.palette:palette-ktx:$version • SQLite KTX - androidx.sqlite:sqlite-ktx:$version • Collection KTX - androidx.collection:collection-ktx:$version • ViewModel KTX - androidx.lifecycle:lifecycle-viewmodel-ktx:$version • Reactive Streams KTX - androidx.lifecycle:lifecycle- reactivestreams-ktx:$version • Navigation KTX - androidx.navigation:navigation-runtime-ktx: $version • WorkManager KTX - androidx.work:work-runtime-ktx:$version • Play Core KTX - com.google.android.play:core-ktx:$version https://developer.android.com/kotlin/ktx
31. DISCOVERABILITY
32. DISCOVERABILITY
33. ¿ENTONCES TIRO TODO? https://developer.android.com/kotlin/ktx class TextUtils { static boolean isEmailValid(String str) { // } }
34. ¿ENTONCES TIRO TODO? https://developer.android.com/kotlin/ktx class TextUtils { static boolean isEmailValid(String str) { // } } inline fun String.isEmailValid = TextUtils.isEmailValid(this)
35. ¿ENTONCES TIRO TODO? https://developer.android.com/kotlin/ktx class TextUtils { static boolean isEmailValid(@NonNull String str) { // } } inline fun String.isEmailValid = TextUtils.isEmailValid(this)
36. ¿ENTONCES TIRO TODO? https://developer.android.com/kotlin/ktx class TextUtils { @ExtensionFunction static boolean isEmailValid(@NonNull String str) { // } } inline fun String.isEmailValid = TextUtils.isEmailValid(this)
37. ¿ENTONCES TIRO TODO? https://developer.android.com/kotlin/ktx class TextUtils { @ExtensionFunction static boolean isEmailValid(@NonNull String str) { // } }
38. KEEP-110 https://github.com/Kotlin/KEEP/issues/110 • @ExtensionFunction / @ExtensionProperty
 Turn a static method with at least one argument into an extension
 function or an extension property. • @ParameterName - An explicit name for parameters. • @DefaultValue - Default parameter values.
39. TITLE
40. ¿POR QUÉ DEBERÍA IMPORTAR? Estas técnicas hacen el desarrollo en Android mas conciso y agradable Código más legible = mayor facilidad = menos bugs = más divertido :)
41. SOBRECARGA DE OPERADORES a++ a— a + b a +=b a[i] a[i] = 1 …
42. SOBRECARGA DE OPERADORES // Original bitmap.getPixel(100, 100) // KTX bitmap[100, 100]
43. SOBRECARGA DE OPERADORES inline operator fun Bitmap.get(x: Int, y: Int) = getPixel(x, y)
44. SOBRECARGA DE OPERADORES inline operator fun Bitmap.get(x: Int, y: Int) = getPixel(x, y)
45. SOBRECARGA DE OPERADORES inline operator fun Bitmap.get(x: Int, y: Int) = getPixel(x, y)
46. SOBRECARGA DE OPERADORES // Original rect1.union(rect2) // KTX rect1 + rect2
47. SOBRECARGA DE OPERADORES inline operator fun Rect.plus(r: Rect) { return Rect(this).apply { union(r) } }
48. SOBRECARGA DE OPERADORES inline operator fun Rect.plus(r: Rect) { return Rect(this).apply { union(r) } }
49. SOBRECARGA DE OPERADORES https://kotlinlang.org/docs/reference/operator-overloading.html
50. DECONSTRUCCÍON val finalRect = rect1 + rect2 val left = finalRect.left val right = finalRect.right val top = finalRect.top val bottom = finalRect.bottom
51. DECONSTRUCCÍON val finalRect = rect1 + rect2 val (left, right, top, bottom) = finalRect
52. DECONSTRUCCÍON inline operator fun Rect.component1() = this.left inline operator fun Rect.component2() = this.right inline operator fun Rect.component3() = this.top inline operator fun Rect.component4() = this.bottom
53. DECONSTRUCCÍON inline operator fun Rect.component1() = this.left inline operator fun Rect.component2() = this.right inline operator fun Rect.component3() = this.top inline operator fun Rect.component4() = this.bottom
54. RESUMEN • Extension Functions nos ayudan a • Código más legible • Menor posibilidad de errores • Mayor facilidad para descubrir funcionalidad • Mayor expresividad
55. MUCHAS GRACIAS @Gazeria Ricardo Markiewicz androidedelvalle Ricardo Markiewicz <ricardo.markiewcz@gmail.com> Android Engineer at