Intermediate quizzes – Java interfaces

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 Interfaces


Quiz 1: Implementing interfaces in Java

What happens when the following program is compiled and run?

public interface InterfaceB {

	int NUMBER = 1;
	int method();

public interface InterfaceA extends InterfaceB {

	int NUMBER = 4;

public class MyClass implements InterfaceA {

	int NUMBER = 2;

	public int method(){
		return NUMBER;
	public static void main(String[] args){
		InterfaceA iA = new MyClass();
		InterfaceB iB = new MyClass();
		MyClass mc = new MyClass();
		System.out.print("-v" + mc.NUMBER + "-m" + iB.method());
		System.out.print("-v" + iA.NUMBER + "-m" + iA.method());
		System.out.print("-v" + iB.NUMBER + "-m" + iB.method());

Select the correct answer.

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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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  1. I’m so glad I found my solituon online.

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