java quiz

public class Main {

    public static void main(String[] args) {

        int[] arr = {10, 20, 30, 40, 50};

        int index = 2;

        System.out.println(arr[index + 1]);

    }

}

• 30

• 40

• 50

• Systax error

public class Main {

    public static void main(String[] args) {

        String str = “Hello, world!”;

        System.out.println(str.length());

    }

}

• 13

• 14

• 12

• Undefined behavior

public class Main {

    public static void main(String[] args) {

        int[] Arr = new int[3];

        Arr[1] = 10;

        Arr[2] = 20;

        Arr = null;

        System.out.println(arr[2]);

    }

}

• 0

• 10

• 20

• NullPointerException

public class Main {

    public static void main(String[] args) {

        int[] arr = new int[10];

          Arr = null;

        Arr[0] = 5;

        System.out.println(arr[0]);

    }

}

What will happen?

• It will print 5.

• It will print 0

• It will throw a NullPointerException

• It will cause a compilation error.

public class Main {

    public static void main(String[] args) {

        int x = 5; // Binary: 0101

        x= x << 1;

        System.out.println(x);

    }

}

• 5

• 10

• 20

• 2

public class Main {

    static class Person {

        String name;

        int age;

        Person(String name, int age) {

            this.name = name;

            this.age = age;

        }

    }

    public static void main(String[] args) {

        Person[] persons = {new Person(“John”, 25), new Person(“Jane”, 30)};

        System.out.println(persons[1].age);

    }

}

• persons[1].name

•  persons[0].age

• persons[1].age

• persons[0].name

public class Main {

    public static void main(String[] args) {

        int I = 0;

        while (I >= 0) {

            System.out.print(I + “ “);

        }

    }

}

• The loop will terminate after one iteration

• The loop will run forever.

• The loop will run 0 iterations.

• It will cause an exception

public class Main {

    public static void changeValue(int x) {

        x=10;

    }

    public static void main(String[] args) {

        int num = 5;

        changeValue(num);

        System.out.println(num);

    }

}

• 5

• 10

• Compilation error

• Undefined behavior

public class Main {

    public static void main(String[] args) {

        int x = 5;

        x = x ^ 3;

        System.out.println(x);

    }

}

• 125

• 2

• 8

• 15

public class Main {

    public static void func() {

        int x = 5;

        System.out.print(x + “ “);

        x++;

    }

    public static void main(String[] args) {

        func();

        func();

        func();

    }

}

• 5 5 5

• 5 6 7

• 6 6 6

• Compilation error