Sun Certified Java Programmer (SCJP) Questions

Question 1

What will happen if you compile/run this code?

1: public class Q1 extends Thread

2: {

3:    public void run()

4:    {

5:       System.out.println("Before start method");

6:       this.stop();

7:       System.out.println("After stop method");

8:    }

9:

10:   public static void main(String[] args)

11:   {

12:      Q1 a = new Q1();

13:      a.start();

14:   }

15: }

 

A) Compilation error at line 7.

B) Runtime exception at line 7.

C) Prints "Before start method" and "After stop method".

D) Prints "Before start method" only.

Answer : D

Explanation : After the execution of stop() method, thread won't execute any more statements.

 

Question 2

What will happen if you compile/run the following code?

1:    class Test

2:    {

3:       static void show()

4:       {

5:          System.out.println("Show method in Test class");

6:       }

7:    }

8:

9:    public class Q2 extends Test

10:   {

11:      static void show()

12:      {

13:          System.out.println("Show method in Q2 class");

14:      }

15:      public static void main(String[] args)

16:      {

17:           Test t = new Test();

18:           t.show();

19:           Q2 q = new Q2();

20:           q.show();

21:

22:           t = q;

23:           t.show();

24:

25:           q = t;

26:           q.show();

27:      }

28:  }

 

A) prints "Show method in Test class"

"Show method in Q2 class"

"Show method in Q2 class"

"Show method in Q2 class"

 

B) prints "Show method in Test class"

"Show method in Q2 class"

"Show method in Test class"

"Show method in Test class"

 

C) prints "Show method in Test class"

"Show method in Q2 class"

"Show method in Test class"

"Show method in Q2 class"

 

D) Compilation error.


 

Answer : D

Explanation : Explicit casting is required at line 25.

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