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Question 7
What output is produced by the program shown in Listing 7 ?
- A. Compiler Error
- B. Runtime Error
- C. A-intfcMethodX B-intfcMethodX
- D. None of the above.
Listing 7 . Listing for Question 7.
public class Ap137{
public static void main(String args[]){new Worker().doIt();
}//end main()}//end class Ap137
class Worker{void doIt(){
Object[]myArray = new Object[2];myArray[0] = new A();myArray[1] = new B();for(int i=0;i<myArray.length;i++){
((X)myArray[i]).intfcMethodX();
}//end for loopSystem.out.println("");
}//end doIt()}// end class Worker
class Base{public void inherMethod(){
System.out.print("Base ");}//end inherMethod()
}//end class Baseclass A extends Base implements X{
public void inherMethod(){System.out.print(
" A-inherMethod ");}//end inherMethod()public void intfcMethodX(){
System.out.print("A-intfcMethodX ");
}//end intfcMethodX()}//end class A
class B extends Base implements X{public void inherMethod(){
System.out.print(" B-inherMethod ");
}//end inherMethod()public void intfcMethodX(){System.out.print(
"B-intfcMethodX ");}//end intfcMethodX()
}//end class Binterface X{
public void intfcMethodX();}//end X
Question 8
What output is produced by the program shown in Listing 8 ?
- A. Compiler Error
- B. Runtime Error
- C. A-intfcMethodX B-intfcMethodX
- D. None of the above.
Listing 8 . Listing for Question 8.
public class Ap138{
public static void main(String args[]){new Worker().doIt();
}//end main()}//end class Ap138
class Worker{void doIt(){
X[]myArray = new X[2];myArray[0] = new A();myArray[1] = new B();for(int i=0;i<myArray.length;i++){
myArray[i].intfcMethodX();
}//end for loopSystem.out.println("");
}//end doIt()}// end class Worker
class Base{public void inherMethod(){
System.out.print("Base ");}//end inherMethod()
}//end class Baseclass A extends Base implements X{
public void inherMethod(){System.out.print(
" A-inherMethod ");}//end inherMethod()public void intfcMethodX(){
System.out.print("A-intfcMethodX ");
}//end intfcMethodX()}//end class A
class B extends Base implements X{public void inherMethod(){
System.out.print(" B-inherMethod ");
}//end inherMethod()public void intfcMethodX(){System.out.print(
"B-intfcMethodX ");}//end intfcMethodX()
}//end class Binterface X{
public void intfcMethodX();}//end X
Question 9
What output is produced by the program shown in Listing 9 ?
- A. Compiler Error
- B. Runtime Error
- C. Base A B
- D. None of the above.
Listing 9 . Listing for Question 9. |
---|
public class Ap139{
public static void main(String args[]){new Worker().doIt();
}//end main()}//end class Ap139
class Worker{void doIt(){
Base myVar = new Base();myVar.test();
myVar = new A();myVar.test();
myVar = new B();myVar.test();
System.out.println("");}//end doIt()
}// end class Workerclass Base{
public void test(){System.out.print("Base ");
}//end test()}//end class Base
class A extends Base implements X,Y{public void test(){
System.out.print("A ");}//end test()
}//end class Aclass B extends Base implements X,Y{
public void test(){System.out.print("B ");
}//end test()}//end class B
interface X{public void test();
}//end Xinterface Y{
public void test();}//end Y |
Read also:
OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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