Where are the following functions dened, and what do they do? Random(), abs(), nextDouble(), append()

public class SomeFormats {

public static void main(String args[]) {

int x = 20;

float y = 5.5f;

char c = 'J';

String str = "Hello Java"

//Displaying formatted string

System.out.printf("The formatted string: %d %f %c %s", x , y, c, str);

}

}