Beginner quizzes – Java language fundamentals

Written By Sar Maroof - Sarmaroof.com

The following Java exercise(s) are designed for beginner level programmers. If the level is too hard, then I recommend reading my article about this topic, which offers a theoretical explanation including more exercises. .

Choose a level: Beginner Intermediate Advanced

Quiz 1: Java wrapper classes “Integer” objects

What happens when you try to compile and run the following program?

public class MyClass {

    public static void main(String[] args) {
        Integer integer1 = new Integer("5");
        Integer integer2 = new Integer("5");
        Object obj1 = (Object) integer1;
        Object obj2 = (Object) integer2;

        if (obj1.equals(obj2)) {
            System.out.print("e");
        } else {
            System.out.print("f");
        }
    }
}

Quiz 2: Java Strings

What happens when you try to compile and run the following program?

class MyClass {

	public static void main(String[] args){
		String str1 = new String("string");
		String str2 = new String("string");
		if(str1 == str2) {
			System.out.print("n");
		}else {
			System.out.print("o");
		}
		if(str1.equals(str2)) {
			System.out.print("p");
		}else {
			System.out.print("q");
		}
	}
}

Quiz 3: Using “String” method indexOf

What does the following code do?

public class MyClass {

	public void method(){
		String str = "abcde";
		System.out.print(str.indexOf("d"));
	}
	public static void main(String[] args){
		MyClass mc = new MyClass();
		mc.method();
	}
}