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Passing data between AndroidActivities

Sending data private void openVideoActivity(String video) { Intent newActivity = new Intent(this, PlayerActivity.class); newActivity.putExtra(“videoId”, video); startActivity(newActivity); } Retrieving data final String videoID = getIntent().getExtras().getString(“videoID”);   In Kotlin it looks like this: val intent = Intent(this, NewActivity::class.java).apply { putExtra(“EXTRA_MESSAGE”, “Test 123”) } startActivity(intent) Retrieving val message = intent.getStringExtra(“EXTRA_MESSAGE”) Further Reading Passing data between fragments using SafeArgs…

Android App Lifecycle

Code class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) Log.d(“LifecycleTest”, “onCreate”) } override fun onStart() { super.onStart() Log.d(“LifecycleTest”, “onStart”) } override fun onResume() { super.onResume() Log.d(“LifecycleTest”, “onResume”) } override fun onPause() { super.onPause() Log.d(“LifecycleTest”, “onPause”) } override fun onSaveInstanceState(outState: Bundle) { super.onSaveInstanceState(outState) Log.d(“LifecycleTest”, “onSaveInstanceState”) } override fun onRestoreInstanceState(savedInstanceState: Bundle) { Log.d(“LifecycleTest”,…

Learning Kotlin – Part 6 – functions

This time we look at functions. Let’s take a simple function from Java: public int mult(int num1, int num2){ return num1 * num2; } In Kotlin it would look like this: fun mult(num1: Int, num2: Int): Int{ return num1 * num2 } A function definition always starts with the keyword fun. That’s fun isn’t it?…

Learning Kotlin – Part 5 – loops

This time we deal with loops Loops Kotlin has two types of loops: for and while. For-loop for(x in 1..10){ println(“Loop: $x”) } We can count backwards as well for (x in 10 downTo 1) { println(“Loop: $x”) } While-loop var i = 10 while(i > 0) { println(“$i”) i– } Break & Continue for(x…

Learning Kotlin – Part 3 – ranges

After Learning Kotlin  –  Part 1 and Learning Kotlin – Part 2 we will now dive into the ranges. One nice little feature is the .. syntax: you can generate an IntRange object just by specifying the start and the end element: val oneTo10 = 1..10 You can even use values for the start and…

Learning Kotlin – Part 2 – Arrays

In Learning Kotlin – Part 1 we looked at some basic concepts like type inference and string handling. In this part we deal with arrays: You can easily create an array with the arrayOf function var myArray = arrayOf(1, 1.23, “Jörn”) Element access You can access arrays directly with the [] operator println(myArray[2]) myArray[1] =…