Function

public void println(String x){
	if(x == null){
		x = "null";
	}
	try {
		ensureOpen();
		textOut.write(x);
	} catch(IOException e){
		trouble = true;
	}
	newLine();
}

boolean playButton; 

public void playMusic(){
    if (playButton){
        System.out.println("Music is playing");
    } else {
    	System.out.println("Music is paused");
    }
}

parameter and argument

public void greeting(String location){
	System.out.println("Hello, " + location);
}

public int likePhoto(int currentLikes, String comment, boolean like){
	System.out.println("Feedback: "+ comment);
	if(like){
		currentLikes = currentLikes + 1;
	}
	System.out.println("Number of likes: " + currentLikes);
	return currentLikes;
}

public double makeChange(double itemCost, double dollarsProvided){
	double change = dollarsProvided - itemCost;
	return change;
}

random number

double randomNumber = Math.random();
randomNumber = randomNumber * 10;
int randomInt = (int) randomNumber;

public int rollDice(){
	double randomNumber = Math.random();
	randomNumber = randomNumber * 6 + 1;
	int randomInt = (int) randomNumber;
	return randomInt;
}

java documentation
https://docs.oracle.com/javase/8/docs/api/java/lang/package-summary.html

Math.random()
https://docs.oracle.com/javase/8/docs/api/java/lang/Math.html#random–