ViksaaSkool

public class DrawableMatcher extends TypeSafeMatcher<View> {

    private final int expectedId;
    private String resourceName;
    private int isAnimatedDrawable = -1;

    private int randomFrame = 0;

    public DrawableMatcher(int expectedId) {
        super(View.class);

ViksaaSkool

import android.content.Context;
import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.util.Log;

import java.io.IOException;

/**
 * Created by viksaaskool on 13-04-2017.
 */

ViksaaSkool

/* Declaring variables */

//[val/var] name_of_variable : [type] = value 
//no need for ; at the end of the line 
val a: Int = 1
var b: String = "NullPointerException is dead"
var c: Double? = 0.4

//val - read only value, constant

ViksaaSkool

//A higher-order function is a function that takes functions as parameters, or returns a function. kotlin has the power 
//to pass around functions 

/* Lambdas */
//by definition, lambda expressions are functions that are not declared, but passed immediately as an expression
//surrounded by curly braces and the body goes after ->

//very basic definition
val sum = { x: Int, y: Int -> x + y }

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//

ViksaaSkool

//we have class called Delegate that defines how to get and set values 
class Delegate {
    operator fun getValue(thisRef: Any?, property: KProperty<*>): String {
        return "$thisRef, thank you for delegating '${property.name}' to me!"
    }
 
    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) {
        println("$value has been assigned to '${property.name}' in $thisRef.")
    }
}

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/* With */
//receives an object, and a function that will be executed as an extension function, which means that with can be used
//inside of a function to refere to the object, i.e. do something "with"
inline fun <T, R> with(receiver: T, f: T.() -> R): R = receiver.f()

//example
fun getPersonFromDeveloper(developer: Developer): Person {
    return with(developer) {
        Person(developerName, developerAge)
    }

ViksaaSkool

//One very powerful example of Generics might in combination with delegates is creation of SharedPreferences support
//taken from Kotlin for Android Developers by Antonio Leiva

class MyKotlinSharedPreference<T>(val context: Context, val name: String, val default: T) {

  val prefs by lazy {
     context.getSharedPreferences("default", Context.MODE_PRIVATE)
 }

  //operator overloading

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