1. ► 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];
2. ► 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); } }
3. ► What would be correct output of following program?
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class VQCourse { public String courseName; public int courseID; } public class VirtuQCourseProvide { public static void main(String[]args) { VQCourse course1 = new VQCourse(); course1.courseID = 0001; course1.courseName = "0001"; VQCourse course2 = new VQCourse(); course2 = course1; System.out.println("course1.courseID = " + course1.courseID + ", course2.courseID = " + course2.courseID); }}
4. ► 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 }
5. ► Select correct option(s) about class Object.
6. ► Which of following statement(s) can result in new object instance creation if executed successfully.
7. ► 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()); }}
8. ► Select correct statements about class(es).
9. ► 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); } }
10. ► 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(); }