My adventures in code & business
In Part 1 we dealt with the simplest form of initialization with the primary constructor:
class Planet(
val diameter: Int,
val distanceToSun: Double,
val mass: Double
)
But wait: there is more: Continue reading “Classes in Kotlin – Part 2”
Add the following to your dependencies
implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.2.0")
In Passing data between fragments using SafeArgs I showed You how to pass data between -well- fragments.
This included all basic / built-in types like Strings and Integers.
In this part I will show you how you can pass custom objects. Continue reading “Pass custom objects via SafeArgs”
In Log4j2 for Kotlin I’ve showed you how to configure a basic logger with log4j2.
If you use a PatternLayout like this Continue reading “Log4j2 PatternLayout Cheatsheet”
Logging is a common good practice in software engineering. It enables you to monitor applications in production to gather information about crashes and other malfunctions for further analysis. It is the “little brother” of debugging and often a precursor for setting up test cases which can lead to reproducing the bugs on the developers machine.
Log4j2 is version 2 of the very famous Apache logging library log4j from the Java ecosystem.
This article describes a minimal working solution for log4j2 with Kotlin and Gradle.
To get started with log4j2 add the following lines to your build.gradle file in the dependency section:
compile "org.apache.logging.log4j:log4j-api-kotlin:1.0.0" compile "org.apache.logging.log4j:log4j-api:2.11.1" compile "org.apache.logging.log4j:log4j-core:2.11.1"
If you are using gradle and you want to run a Kotlin script you have to add the following to your build.gradle file
dependencies {
implementation "org.jetbrains.kotlin:kotlin-stdlib"
compile group: 'org.jetbrains.kotlin', name: 'kotlin-script-runtime', version: '1.4.32'
}
private void openVideoActivity(String video) {
Intent newActivity = new Intent(this, PlayerActivity.class);
newActivity.putExtra("videoId", video);
startActivity(newActivity);
}
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")
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", "onSaveInstanceState")
}
override fun onStop() {
super.onStop()
Log.d("LifecycleTest", "onStop")
}
override fun onDestroy() {
super.onDestroy()
Log.d("LifecycleTest", "onDestroy")
}
}
This is a pretty quick one:
Kotlin has the standard Java if / else if / else statements Continue reading “Learning Kotlin – Part 4”
I wanted to try writing an Android app. In spite of using plain old Java I wanted to give the new kid on the block Kotlin (from the Jetbrains folks) a try.
Coming from a Python background it’s good to see that Kotlin doesn’t use semi-colons! But the curly braces from Java make code blocks are still there, hmpf… Continue reading “Learning Kotlin – Part 1”