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[All Quizzes] → [Programming With Java] → [Object Oriented Concepts]


1. ► Code below has class VQClassB which inherits another class VQClassA, study following code carefully and choose correct option about program output.

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package com.vq.classes;

public class VQClassB {
    class VQClassA {
        public VQClassA(int x) {
            this.x = x;
        } protected int x;
    } public VQClassB(int x, int x2, int y) {
        x = x2;
        this.y = y;
    }

    private VQClassB(int x, int y) {
        this.x = x;
        this.y = y;
    }

    private int x;

    private int y;

    public static void main(String[]args) {
        VQClassB vqb = new VQClassB(20, 10);

        VQClassB.VQClassA vqa = new VQClassB(10, 10).new VQClassA(10);

        System.out.println(vqa.x + " " + vqb.x);
    }
}
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2. ► Following program have compilation error, can you guess root cause of it?

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abstract class VQCourse {
    public String courseName;
    public String courseID;
} public class VirtuQCourseProvide extends VQCourse {

    public static void main(String[]args) {
        VQCourse course1 = new VQCourse();
         course1.courseID = "0001";
         course1.courseName = "JAVA";
         System.out.println(course1.toString());
}}
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3. ► Class VQCourse contains declaration about a course, which is inside package com.vq . You are declaring a new class VirtuQCourseProvider where you want to create a object of VQCourse but following program fails to compile. Choose option which eliminates compilation error.

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public class VirtuQCourseProvide {
    public static void main(String[]args) {
        VQCourse course1 = new VQCourse();
}}
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4. ► What is a object?

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5. ► Which of following statement(s) can result in new object instance creation if executed successfully.

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6. ► Choose correct equivalent statement of following code.

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int[][] arr = new int[3][];

for (int i = 0; i < arr.length; i++)
    arr[i] = new int[3];
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7. ► Java is an object oriented programming language which where you declare the class which is type of object you just identified. The objects have states and behaviours which are methods in class.

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8. ► Select correct statements about class(es).

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9. ► You only want to declare the behaviour of a certain type without any implemention , you should declare it as interface. In its most common form, an interface is a group of related methods with empty bodies.

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package com.vq.inheritance;

public interface VQCourse {

    public void printCourseDetail();

    public void getCoursePrice();

}
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10. ► Java provided mechanism where classes can inherit commonly used state and behaviour of other classes.

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package com.vq.inheritance;

public class VQJavaCourse extends VQCourse {
//Some implementation 
}
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