Intermediate quizzes – Java casting object

The following Java exercise(s) are designed for intermediate level programmers. If the level is too hard, then I recommend to select an easier one or you might consider reading my article about this topic, which offers a theoretical explanation including more exercises. Read More: Java Object Casting

Article: Java casting object Quizzes: Beginner  Intermediate  Advanced

Quiz 1: Casting objects in Java

What will happen if you try to compile and execute the main method?

public class MySuper {

	protected int i = 3;

	public MySuper() {
		i ++ ;
		System.out.print("-x" + method(5));
	}
	public int method(){
		return i + i;
	}
	public int method(int i){
		return method() + i;
	}
}

public class MySub extends MySuper {

	int i = 4;

	public int method(){
		return i * i + super.i;
	}
	public static void main(String[] args){
		MySuper mySuper = new MySuper();
		MySuper Mysub = new MySub();
	}
}

Quiz 2: Upcasting and downcasting objects in Java

What happens when the following program is compiled and run?

public class Super {

	protected int x = 3;

	public int method(){
		return x + 5;
	}
	public int method(int x){
		return method() + x;
	}
}

public class Sub extends Super {

	int x = 7;

	public int method(){
		return x * 4 + super.x;
	}
	public static void main(String[] args){
		Super s = new Sub();
		Sub su = (Sub) s;
		Super sup = new Super();
		System.out.print("-" + s.x + "-" + s.method(3) 
                                 + "-" + su.x + "-" + sup.method(3));
	}
}

Please, leave your questions, feedback and suggestions in the comments below!
SarMaroof.com offers a practical method to learn and improve your Java skills. It avoids unnecessary long boring theoretical explanations, but it uses many exercises and quizzes.

Article: Java casting object Quizzes: Beginner  Intermediate  Advanced

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Sar Maroof is graduated from HBO Amsterdam "higher professional education". He is a professional computer programming teacher, gives master classes and publishes technical articles. His experience with developing software started from 2001 and he has worked as a software developer for several big as well as small companies and later as a freelancer. He is the author of Java quizmaster and Build a Java application in 7 days.

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