SCJP Questions 41-50

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Question 41
41. Given:
10. class One {
11. public One foo() { return this; }
12. }
13. class Two extends One {
14. public One foo() { return this; }
15. }
16. class Three extends Two {
17. // insert method here
18. }
Which two methods, inserted individually, correctly complete the Three
class? (Choose two.)
A. public void foo() { }
B. public int foo() { return 3; }
C. public Two foo() { return this; }
D. public One foo() { return this; }
E. public Object foo() { return this; }
Answer: CD

Question 42
Given:
10. class One {
11. void foo() {}
12. }
13. class Two extends One {
14. //insert method here
15. }
Which three methods, inserted individually at line 14, will correctly
complete class Two? (Choose three.)
A. int foo() { /* more code here */ }
B. void foo() { /* more code here */ }
C. public void foo() { /* more code here */ }
D. private void foo() { /* more code here */ }
E. protected void foo() { /* more code here */ }
Answer: BCE

Question 43
Click the Exhibit button.
1. public interface A {
2. public void doSomething(String thing);
3. }
1. public class AImpl implements A {
2. public void doSomething(String msg) { }
3. }
1. public class B {
2. public A doit() {
3. // more code here
4. }
5.
6. public String execute() {
7. // more code here
8. }
9. }
1. public class C extends B {
2. public AImpl doit() {
3. // more code here
4. }
5.
6. public Object execute() {
7. // more code here
8. }
9. }
Which statement is true about the classes and interfaces in the
exhibit?
A. Compilation will succeed for all classes and interfaces.
B. Compilation of class C will fail because of an error in line 2.
C. Compilation of class C will fail because of an error in line 6.
D. Compilation of class AImpl will fail because of an error in line 2.
Answer: C

Question 44
Click the Exhibit button.
1. public class A {
2. public String doit(int x, int y) {
3. return “a”;
4. }
5.
6. public String doit(int... vals) {
7. return “b”;
8. }
9. }
Given:
25. A a=new A();
26. System.out.println(a.doit(4, 5));
What is the result?
A. Line 26 prints “a” to System.out.
B. Line 26 prints ‘b” to System.out.
C. An exception is thrown at line 26 at runtime.
D. Compilation of class A will fail due to an error in line 6.
Answer: A

Question 45
Given:
1. public class A {
2. public void doit() {
3. }
4. public String doit() {
5. return “a”;
6. }
7. public double doit(int x) {
8. return 1.0;
9. }
10.}
What is the result?
A. An exception is thrown at runtime.
B. Compilation fails because of an error in line 7.
C. Compilation fails because of an error in line 4.
D. Compilation succeeds and no runtime errors with class A occur.
Answer: C

Question 46
46. Given:
10. class Line {
11. public static class Point { }
12. }
13.
14. class Triangle {
15. // insert code here
16. }
Which code, inserted at line 15, creates an instance of the Point class
defined in Line?
A. Point p = new Point();
B. Line.Point p = new Line.Point();
C. The Point class cannot be instatiated at line 15.
D. Line 1 = new Line() ; 1.Point p = new 1.Point();
Answer: B

Question 47
Given:
10. class Line {
11. public class Point { public int x,y; }
12. public Point getPoint() { return new Point(); }
13. }
14. class Triangle {
15. public Triangle() {
16. // insert code here
17. }
18. }
Which code, inserted at line 16, correctly retrieves a local instance of a
Point object?
A. Point p = Line.getPoint();
B. Line.Point p = Line.getPoint();
C. Point p = (new Line()).getPoint();
D. Line.Point p = (new Line()).getPoint();
Answer: D

Question 48
Given:
10. class One {
11. public One() { System.out.print(1); }
12. }
13. class Two extends One {
14. public Two() { System.out.print(2); }
15. }
16. class Three extends Two {
17. public Three() { System.out.print(3); }
18. }
19. public class Numbers{
20. public static void main( String[] argv) { new Three(); }
21. }
What is the result when this code is executed?
A. 1
B. 3
C. 123
D. 321
E. The code rims with no output.
Answer: C

Question 49
Click the Exhibit button.
11. class Person {
12. String name = “No name’;
13. public Person(String nm) { name = nm; }
14. }
15.
16. class Employee extends Person {
17. String emplD = “0000”;
18. public Employee(String id) { empID = id; }
19. }
20.
21. public class EmployeeTest {
22. public static void main(String[] args) {
23. Employee e = new Employee(”4321”);
24. System.out.println(e.empID);
25. }
26. }
What is the result?
A. 4321
B. 0000
C. An exception is thrown at runtime.
D. Compilation fails because of an error in line 18.
Answer: D

Question 50
Given:
1. public class Plant {
2. private String name;
3. public Plant(String name) { this.name = name; }
4. public String getName() { return name; }
5. }
1. public class Tree extends Plant {
2. public void growFruit() { }
3. public void dropLeaves() { }
4. }
Which is true?
A. The code will compile without changes.
B. The code will compile if public Tree() { Plant(); } is added to the
Tree class.
C. The code will compile if public Plant() { Tree(); } is added to the
Plant class.
D. The code will compile if public Plant() { this(”fern”); } is added to
the Plant class.
E. The code will compile if public Plant() { Plant(”fern”); } is added to
the Plant class.
Answer: D

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