Java OCA OCP Practice Question 11

Question

Which one statement is true for the following code? 

 1. class MyList extends java.util.Vector 
 2.   implements Runnable { 
 3.     public void run(String message) { 
 4.       System.out.println("in run() method: " + 
 5.       message); /*from  w w w . j a va2 s . c  o  m*/
 6.   } 
 7. } 
 8. 
 9. class MyListTest { 
10.   public static void main(String args[]) { 
12.     MyList g = new MyList(); 
13.     Thread t = new Thread(g); 
14.     t.start(); 
15.   } 
16. }
  • A. Compiler error, because class MyList does not correctly implement the Runnable interface.
  • B. Compiler error at line 13, because you cannot pass a parameter to the constructor of a Thread.
  • C. Compile correctly but will crash with an exception at line 13.
  • D. Compile correctly but will crash with an exception at line 14.
  • E. Compile correctly and will execute without throwing any exceptions. 


A.

Note

The Runnable interface defines a run() method with void return type and no parameters.

The method given in the problem has a String parameter, so the compiler will complain that class MyList does not define void run() from interface Runnable.

B is wrong, because you can pass a parameter to a thread's constructor; the parameter becomes the thread's target.

C, D, and E are wrong.




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