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


1. ► What is a object?

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

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3. ► 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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4. ► 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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5. ► Code below has class VQClassB which inherits another class VQClassA, study following code carefully and choose correct option about output of program.

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package com.vq.classes;

class VQClassA {
    public VQClassA(int x) {
        this.x = x;
    } protected int x;
}

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

    private int x;

    private int y;

    public static void main(String[]args) {
        VQClassA vqa = new VQClassA(10);

        VQClassB vqb = new VQClassB(20, 10);

        vqa = vqb;
        System.out.println(vqa.x + " " + vqb.y);
    }
}
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6. ► 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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7. ► Following is syntax to create a object of class Object. Which statements are true when following statement execute at runtime.

Object obj = new Object();
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8. ► 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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9. ► 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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10. ► Select correct statements about class(es).

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