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();
	}
}

Choose a level: Beginner Intermediate Advanced

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Sar Maroof is a professional software development teacher, gives master classes and publishes technical articles. He is also an expert software developer and worked for several big as well as small companies and later as a freelancer.