Java

What is a class in object-oriented programming?

• A variable that holds multiple values

• A type of exception handling mechanism

• A blueprint for creating objects

• A method that performs calculations

What does encapsulation mean in Java?

• Hiding the implementation details of a class

• Creating multiple instances of a class

• Using class inheritance

• Combining multiple classes into one

Which Java feature allows a subclass to inherit properties and behaviors from a superclass?

• Encapsulation

• Polymorphism

• Abstraction

• Inheritance

What is the output of the following Java program?

public class MyClass {

    int x;

    public MyClass(int val) {

        x = val;

    }

    public static void main(String[] args) {

        MyClass obj = new MyClass(5);

        System.out.println(obj.x);

    }

}

Which of the following statements correctly initializes an array of integers in Java?

• int[] numbers = new int[5]();

• int[] numbers = new int[5];

• int numbers[5];

• int[] numbers = {1, 2, 3, 4, 5};

What is the output (value only) of the following Java program?

public class Circle {

    double radius;

    public Circle(double r) {

        radius = r;

    }

    public double calculateArea() {

        return Math.PI radius radius;

    }

    public static void main(String[] args) {

        Circle c = new Circle(3.0);

        System.out.println( c.calculateArea());

    }

}

How do you access the third element of an array named scores?

• scores.get(3)

• scores.third

• scores[2]

• scores(3)

Which of the following statements creates a two-dimensional array in Java?

• int[][] matrix = new int[3][3];

• int[] matrix = new int[3][3];

• int[][] matrix = new int[3];

• int matrix[][] = new int[3][3];

What is the output of the following Java program?

public class ArraySum {

    public static void main(String[] args) {

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

        int sum = 0;

        for (int i = 0; i < numbers.length; i++) {

            sum += numbers[i];

        }

        System.out.println("Sum: " + sum);

    }

}

What is the correct syntax to declare a constant in Java?

• int MY_CONSTANT = 10;

• final int MY_CONSTANT = 10;

• constant int MY_CONSTANT = 10;

• static final int MY_CONSTANT = 10;