Is this Java quiz free to attempt?

Yes, this Java hard level MCQ quiz is completely free to attempt on Intense Practice Academy and can be used any number of times for practice.

Java Free Questions

HARD LEVEL • JAVA

Hard Level Java Quiz – 30 Questions

Java free questions
Answer all questions and click Submit Quiz to see your score.

Difficulty: Placement Level / Hard

1. What is the output of the following code?

public class Test {
    public static void main(String[] args) {
        int x = 5;
        System.out.println(x++ + ++x);
    }
}

10 12 11 13

2. What will this code print?

public class Test {
    public static void main(String[] args) {
        String s1 = "Java";
        String s2 = new String("Java");
        System.out.println(s1 == s2);
        System.out.println(s1.equals(s2));
    }
}

true true true false false true false false

3. What is the output of this code?

public class Test {
    public static void main(String[] args) {
        int a = 10;
        int b = 20;
        a = a ^ b;
        b = a ^ b;
        a = a ^ b;
        System.out.println(a + " " + b);
    }
}

10 20 20 10 0 0 Compilation error

4. What will be printed?

public class Test {
    public static void main(String[] args) {
        System.out.println(10 + 20 + "Java" + 10 + 20);
    }
}

30Java30 30Java1020 Java1020 1020Java1020

5. What is the output?

public class Test {
    public static void main(String[] args) {
        int i = 0;
        for (; i < 3; ) {
            System.out.print(i + " ");
            i++;
        }
    }
}

0 1 0 1 2 1 2 3 0 1 2 3

6. What happens when this code is compiled and run?

interface A {
    default void show() {
        System.out.println("A");
    }
}
interface B {
    default void show() {
        System.out.println("B");
    }
}
public class Test implements A, B {
    public static void main(String[] args) {
        new Test().show();
    }
}

Prints: A Prints: B Compilation error due to duplicate default methods Runtime exception

7. You have an immutable class in Java. Which one is a necessary condition?

class Point {
    private int x;
    private int y;
    // ...
}

All fields must be public Class must be declared final and fields private with no setters Class must extend Thread Fields must be static

8. What is the output?

public class Test {
    public static void main(String[] args) {
        String s = "abc";
        s.concat("def");
        System.out.println(s);
    }
}

abcdef abc def Compilation error

9. What is the output of this program?

class Parent {
    int value = 10;
}
class Child extends Parent {
    int value = 20;
}
public class Test {
    public static void main(String[] args) {
        Parent p = new Child();
        System.out.println(p.value);
    }
}

10 20 0 Runtime error

Q10

10. Which collection guarantees that insertion order is preserved?

HashSet TreeSet LinkedHashSet PriorityQueue

Q11

11. What happens when this code runs?

public class Test {
    public static void main(String[] args) {
        try {
            System.out.println("Try");
            System.exit(0);
        } finally {
            System.out.println("Finally");
        }
    }
}

Prints: Try Finally Prints: Finally only Prints: Try only Compilation error

Q12

12. What is the output?

public class Test {
    public static void change(String s) {
        s = s + "X";
    }
    public static void main(String[] args) {
        String s = "Hi";
        change(s);
        System.out.println(s);
    }
}

HiX Hi null Compilation error

Q13

13. What will be printed?

public class Test {
    public static void main(String[] args) {
        int a = 5;
        System.out.println(a++ + a++ + ++a);
    }
}

17 18 19 20

Q14

14. What will happen?

public class Test {
    public static void main(String[] args) {
        int[] arr = new int[-5];
        System.out.println(arr.length);
    }
}

Prints: -5 Prints: 0 Throws NegativeArraySizeException at runtime Compilation error

Q15

15. You want a thread-safe list with good read performance and infrequent writes. Which collection is best?

ArrayList Vector CopyOnWriteArrayList LinkedList

Q16

16. What is the output?

public class Test {
    public static void main(String[] args) {
        String s1 = "java";
        String s2 = "ja" + "va";
        System.out.println(s1 == s2);
    }
}

true false Compilation error Runtime exception

Q17

17. Find the error / behaviour:

public class Test {
    public static void main(String[] args) {
        String s = null;
        System.out.println(s.length());
    }
}

Prints: 0 Prints: null Throws NullPointerException at runtime Compilation error

Q18

18. Which statement about overloading and overriding is TRUE?

Overloaded methods must change return type only Overridden methods must have same signature and compatible return type Overloaded methods must be in different classes only Overridden methods must be declared private

Q19

19. What is the output?

class A {
    static void show() {
        System.out.println("A");
    }
}
class B extends A {
    static void show() {
        System.out.println("B");
    }
}
public class Test {
    public static void main(String[] args) {
        A obj = new B();
        obj.show();
    }
}

A B AB Compilation error

Q20

20. What will be printed?

public class Test {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("abc");
        String s = sb.toString();
        sb.append("def");
        System.out.println(s);
    }
}

abcdef abc def null

Q21

21. Which keyword is used to prevent inheritance of a class?

static final private abstract

Q22

22. Find the behaviour of this code:

public class Test {
    public static void main(String[] args) {
        int x = 0;
        System.out.println(10 / x);
    }
}

Prints: 0 Prints: Infinity Throws ArithmeticException at runtime Compilation error

Q23

23. You want to sort a custom class with multiple fields. Which interface should the class implement for natural ordering?

Serializable Cloneable Comparable Comparator

Q24

24. What is the output?

public class Test {
    public static void main(String[] args) {
        boolean b1 = true;
        boolean b2 = false;
        if (b1 = false || b2) {
            System.out.println("Hello");
        } else {
            System.out.println("World");
        }
    }
}

Hello World Compilation error No output

Q25

25. What is the output?

public class Test {
    public static void main(String[] args) {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 2; j++) {
                if (i == 1) break;
                System.out.print(i + "" + j + " ");
            }
        }
    }
}

00 01 10 11 20 21 00 01 20 21 00 01 10 20 21 00 01 02

Q26

26. What happens here?

abstract class A {
    abstract void show();
}
public class Test extends A {
    // missing implementation
}

Compiles successfully Compilation error: Test is not abstract and does not override abstract method Runtime error only show() will be inherited automatically

Q27

27. Which is TRUE about String, StringBuilder, StringBuffer?

String is mutable and thread-safe StringBuilder is mutable and not thread-safe StringBuffer is immutable StringBuilder is thread-safe

Q28

28. What is the output?

class Test {
    static {
        System.out.print("Static ");
    }
    public static void main(String[] args) {
        System.out.print("Main ");
    }
}

Main Static Static Main Static Main

Q29

29. In a try-with-resources statement, which interface must the resource implement?

Serializable Closeable or AutoCloseable Runnable Cloneable

Q30

30. What is the output?

public class Test {
    public static void main(String[] args) {
        int x = 1;
        do {
            System.out.print(x + " ");
            x = x * 2;
        } while (x < 10);
    }
}

1 2 4 8 1 2 4 1 2 4 8 16 Infinite loop

✅ Green – Correct | ❌ Red – Incorrect / Not Attempted

Java Hard Level MCQ Quiz – Frequently Asked Questions

1. Who can use this hard level Java MCQ quiz?

This quiz is designed for final year students, freshers preparing for IT placements, and anyone who already knows Java basics and wants to practice tricky, interview-level questions.

2. What types of questions are included in this quiz?

The quiz includes a mix of output-based questions, error-finding questions, tricky loops, OOP concepts, exception handling, collections and scenario-based problems commonly asked in interviews.

3. How many questions are there and what is the difficulty level?

This quiz contains 30 hard level multiple-choice questions. Most questions are at placement and technical interview difficulty, not beginner level.

4. Will I get answers and score instantly?

Yes. After you click the “Submit Quiz & View Result” button, you will see your total score, number of correct and wrong answers, percentage and the correct option for each question.

5. Is this quiz free to attempt?

Yes, this Java hard level MCQ quiz is completely free to attempt on Intense Practice Academy. You can use it any number of times for practice.

6. How is this quiz helpful for placements and interviews?

These questions help you practice tricky areas like output prediction, pass-by-value behavior, immutability, static methods, collections, exceptions and nested loops, which are very common in technical rounds and online tests.

7. Can I reattempt the quiz multiple times?

Yes, you can reattempt the quiz as many times as you want. Repeating hard questions improves your speed, accuracy and confidence before real exams.

8. Do you have more Java MCQs and other subjects?

Yes. Intense Practice Academy provides more Java MCQ sets, as well as C, Python, Aptitude and Reasoning questions. You can explore our free pages and paid MCQ packs for complete placement preparation.

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