OCPJP 6 Mock Exam -18

1 . What will be the output?

[code lang=”java”]
public class Test1 extends Base{
Test1(long i){}
public static void main(String args[]){}
}
class Base{
Base(int i){}
}
[/code]

Choose the one below:

1. Base(){}
2. Base(long l){}
3. Base(float f){}
4. It will compile properly

2 . What will be the output?

[code lang=”java”]
public class Test2 extends Base{
Test2(long i){
super(2);
}
Test2(){}
public static void main(String args[]){
new Test2(2);
}
}
class Base{
Base(int i){
System.out.println(i);
}
Base(byte i){
System.out.println(i*2);
}
}
[/code]

Choose the one below:

1. 2
2. 4
3. Compiler Error
4. It will compile if we add super(2) in Test2()

3 . which of the following keywords can be applied to constructors?

1. private
2. public
3. void
4. All the above

4 . which of the following are valid constructors?

1. Test4(){}
2. void Test4(){}
3. private Test4(){}
4. All the above

5 . which of the following statements are true?

1. constructors can be overriden
2. constructors can be overloaded
3. constructors can return a value
4. constructors can be static

6 . What will be the output?

[code lang=”java”]
public class Test6{
Test6(int i, int j){
System.out.println("Int");
}
Test6(short i, short j){
System.out.println("Short");
}
Test6(byte i, byte j){
System.out.println("Byte");
}
public static void main(String args[]){
Test6 t = new Test6(1,2);
}
}
[/code]

Choose the one below:

1. Int
2. Byte
3. Short
4. Compiler error

7 . What will be the output?

[code lang=”java”]
public class Test7{
Test7(int i, int j){
System.out.println("Int");
}
Test7(short i, short j){
System.out.println("Short");
}
Test7(byte i, byte j){
System.out.println("Byte");
}
public static void main(String args[]){
byte b1 = 1;
byte b2 = 2;
Test7 t1 = new Test7(b1,b1);
Test7 t2 = new Test7(b1*1,b1*2);
Test7 t3 = new Test7(b1*b1,b1*b2);
}
}
[/code]

Choose the one below:

1. Byte Int Int
2. Byte Byte Byte
3. Byte Int Byte
4. Int Int Int

8 . What will be the output?

[code lang=”java”]
public class Test8 extends Base{
Test8(){}
public static void main(String args[]){}
}
class Base{
Base() throws Exception{}
}
[/code]

Choose the one below:

1. Byte Int Int
2. Byte Byte Byte
3. Byte Int Byte
4. Int Int Int

9 . What will be the output?

[code lang=”java”]
public class Test9 extends Base{
Test9()throws Exception{}
Test9(int i) {}
public static void main(String args[])throws Exception{
new Test9();
}
}
class Base{
Base() throws Exception{
System.out.println("Base");
}
}
[/code]

Choose the one below:

1. Base
2. Compiler Error
3. Runtime exception
4. None of the above

10 . What will be the output?

[code lang=”java”]
public class Test10 extends Base{
Test10(){}
Test10(int i) {}
public static void main(String args[]){
new Test10();
}
}
class Base{
Base() {
System.out.println("Base");
}
Base(int i) throws Exception{
System.out.println("No argument constructor.");
}
}
[/code]

Choose the one below:

1. Base
2. Compiler Error
3. Runtime exception
4. None of the above

11 . What will be the output?

[code lang=”java”]
class Test11 extends B {
private Test11() { super(); }
public Test11(String msg) { this(); }
public Test11(int i) {}
}
class A {
public A() {}
public A(int i) { this(); }
}
class B extends A {
public boolean B(String msg) { return false; }
}
[/code]

Choose the one below:

1. The code will fail to compile
2. The constructor in A that takes an int as argument will never be called as a result of constructing an object of class B or Test11
3. class Test11 has three constructors
4. At most one of the constructors of each class is called as a result of constructing an object of class Test11

12 . Which of the following statements are true?

1. The default constructor has a return type of void
2. The default constructor takes a sungle parameter
3. The default constructor takes no parameters
4. The default constructor is not created if the class has anyconstructors of its own

Answers

1 : 1 is correct. Base(){}.

2 : 4 is correct. It will compile if we add super(2) in Test2().

3 : 1 & 2 is correct.
1 . private
2 . public

4 : 1 & 3 is correct.
1 . Test4(){}
3 . private Test4(){}

5 : 2 is correct. Constructors can be overloaded.

6 : 1 is correct. Int.

7 : 3 is correct. Byte Byte Int.

8 : 3 is correct. Byte Byte Int.

9 : 2 is correct. Compiler Error.

10 : 1 is correct. Base.

11 : 2 & 3 is correct.
2 . The constructor in A that takes an int as argument will never be called as a result of constructing an object of class B or Test11
3 . class Test11 has three constructors

12 : 3 & 4 is correct.
3 . The default constructor takes no parameters
4 . The default constructor is not created if the class has any constructors of its own