Kotlin for Android

Helps not to write boilerplate code with instantiating abstract or interfaces instances. The purpose of the library is to save time of writing code using Android SDK wrapping as much as possible common functionality.

Warning

This project is not relative to JetBrains company or their products. Use this project as is, no author nor anybody else is responsible for any damage.

Linking to Android project

Create regular or use existing Android project in IDEA
Clone this project in the parent folder of your project
Write in the file setting.gradle:

include ':kotlinandroidlib'
project(':kotlinandroidlib').projectDir=new File('../kotlinAndroidLib/app')

Write in the module build.gradle in Android dependencies:

compile project(':kotlinandroidlib')

do a gradle Sync and voila!

Usage

Small example of usage most of the functions and also some examples like how to create Parcelable. See Sample Activity

findViewById replacement for Activity and View:

  val myButton = findView<Button>(R.id.my_button)

setOnClickListener for Views:

  myView?.setOnClickListener { /* code here */ }
  myView?.setOnClickListener { view -> /* code here with view: View? argument */ }
  val onClickListener = OnClickListener { view -> /* code here */ }

  myView?.setOnTouchListener { view, event -> false /* with view: View? and event: MotionEvent? */ }
  val onTouchListener = OnTouchListener { view, event -> false }

runOnUiThread for Activities:

It can be used without the library:
```
  runOnUiThread(runnable { /* action */})
```
Library just remove runnable call and can be used as:
```
  runOnUiThread { /* action */ }
```

Short definition of BroadcastReceiver:

Library just wraps onReceive call:

  val myBroadcastReceiver = BroadcastReceiver { context, intent ->
      /* handle intent here */
  }

setPositiveButton and setNegativeButton for AlertDialog.Builder:

  AlertDialog.Builder(this).setTitle("Hello")
      ?.setMessage("Want to say hello to world?")
      ?.setPositiveButton("Yes", { dialog, which -> /* hello */ })
      ?.setNegativeButton("No", { dialog, which -> /* no hello now */ })
      ?.create()

  val positiveButton = dialogOnClickListener { dialog, which -> }

Short definition of OnEditorActionListener:

Library just wraps onEditorAction call:

  val myEditorActionListener = OnEditorActionListener { v, actionId, event ->
      /* handle actionId and/or event */
      false
  }

  myEditText?.setOnEditorActionListener /* OnEditorActionListener */ { v, actionId, event ->
      false
  }

getSystemService with or without casting for known services:

Library allows call with casting for specific name of the service or call directly for known services:
```
  val inputMethodManager = getSystemServiceAs<InputMethodManager>(Context.INPUT_METHOD_SERVICE)
  val inputMethodManager = getInputMethodService()
```

AdapterView<out Adapter?>.setOnItemClickListener and AdapterView<out Adapter?>.setOnItemLongClickListener:

  listView.setOnItemClickListener { parent, view, position, id -> }
  listView.setOnItemLongClickListener { parent, view, position, id -> false }

Wrap calls without runnable() for Handler:

  val handler = Handler()
  handler.post { /* code here */ }
  handler.postDelayed(100) { /* code here */ }
  handler.postAtFrontOfQueue { /* code here */ }
  handler.postAtTime(System.currentTimeMillis() + 100) { /* code here */ }

Also easy to create handler with callback to handle messages:

  val handler = Handler { message ->
      when (message.what) {
          1 -> handleMessage1(message.getData())
          else -> false
      }
  }

Wrap SQLiteDatabase functionality:

Wrap pattern: beginTransaction -> setTransactionSuccessful -> endTransaction with try and finally:

  sqliteDatabase.transaction {
      // call any method of SQLiteDatabase without . or ?.
      execSQL("ALTER TABLE table_1 RENAME TO table_2")
  }

Wrap pattern: cursor not null -> moveToFirst -> moveToNext in do-while loop -> close with try and finally:

  // query call with same arguments + last argument is a body in the loop
  val collection /* of String */ = sqliteDatabase.query<String>("people", array("first_name"), null, null, null, null, null, null) {
      /* Cursor namespace */
      getString(getColumnIndexOrThrow("first_name"))
  }

Support also queryWithFactory, rawQuery and rawQueryWithFactory.

Wrap ContentValues for insert and update:

  sqliteDatabase?.insert("table_name", null) {
      // ContentValues namespace
      put("column_text", "Hello")
      put("column_int", 12.toInt())
      put("column_float", 13.toFloat())
  }

  sqliteDatabase?.update("table_name", "ID = ?", array("3")) {
      // ContentValues namespace
      put("column_text", "Hello World")
  }

Wrap Cursor pattern moveToFirst -> moveToNext in do-while loop:

Possible to call all functions on Cursor?, if Cursor? == null, returns empty collection

  try {
      val collection /* Of String? */ = cursor.map {
          getString(getColumnIndexOrThrow("first_name"))
      }
  } finally {
      cursor?.close()
  }

  val collection = LinkedList<String?>()
  try {
      cursor.mapTo(collection) {
          getString(getColumnIndexOrThrow("first_name"))
      }
  } finally {
      cursor?.close()
  }

  val collection /* Of String? */ = cursor.mapAndClose {
      getString(getColumnIndexOrThrow("first_name"))
  }

ExecutorService:

  executorService.execute { /* code here */ }
  val future = executorService.submit<Any?> { /* code here and no result */ }
  val future = executorService.submit<String?> { /* code here */ "Result" }
  val future = executorService.submit<String?>("Result") { /* code here and result */ }

Wrap Intent, now easy to create new Intent without defining new variable:

  sendBroadcast(Intent() { setAction(Intent.ACTION_DEFAULT) })
  startActivity(Intent(Intent.ACTION_VIEW) { setDataAndType(Uri.parse("http://example.com/audio.mp3"), "audio/mpeg") })

or make it even nicer if you have an action and it's a String value:

  "my.application.intent.action.ACTION_MINE" toIntent {
      /* namespace of Intent */
  }

or just convert String to Intent:

  "my.application.intent.action.ACTION_MINE".toIntent()

Wrap IntentFilter, now easy to create new IntentFilter without defining new variable:

  registerReceiver(broadcastReceiver, IntentFilter {
      addAction(ACTION_HELLO)
  })

Wrap Bundle, now easy to create new Bundle without defining new variable:
```
  Bundle { putString("result", "Some result!") }
```

Short definition of ResultReceiver:

Library just wraps onReceiveResult call:

  val myResultReceiver = ResultReceiver(Hanlder()) { code, data ->
      /* handle result here */
  }

or automatically create new Hanlder

  val myResultReceiver = ResultReceiver { code, data ->
      /* handle result here */
  }

Wrap 'CREATOR' for Parcelable. Example of usage:

WARNING: It might wrong or not supported yet!

  class MyParcelable(val number: Int, val text: String?) : Parcelable {

      public override fun writeToParcel(p0: Parcel?, p1: Int) = if (p0 != null) {
          p0.writeInt(number)
          p0.writeString(text)
      }

      public override fun describeContents(): Int = 0

      class object {

          val CREATOR = CreateParcelable<MyParcelable> { MyParcelable(it.readInt(), it.readString()) }
      }
  }

Wrap Thread, run and call start method:
```
  async {
      // some code here
  }
```

Credits

Vladimir Lichonos Julien Quiévreux

letroll / kotlinAndroidLib

Kotlin for Android

Warning

Linking to Android project

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