Thread Doubts

[Micheal John]

From web page

    
class A extends Thread {
  public A(Runnable r) {super(r);}
  public void run() {System.out.print("A");}
}
class B implements Runnable {
  public void run() {System.out.print("B");}
}
class C {
  public static void main(String[] args) {
    new A(new B()).start();
}}
 
What is the result of attempting to compile and run the program? 
 
a.  Prints: A 
b.  Prints: B 
c.  Prints: AB 
d.  Prints: BA 
e.  Compile-time error 
f.  Run-time error 
g.  None of the above 
 

How the output is a? pls expalain

[Henry Wong]

You are creating an A object, and calling it's start() method -- which in turns calls the run() method. This run() method prints the "A".

The A method does set the runnable of the object to B, but since you overridden the run() method of A, it doesn't call it anymore.

Henry

[Ignacio Cavero]

You are using the new A(Thread t) constructor for A that it is inheriting from the Thread class. Because of that, without noticing you are starting the run method of the runable Object B instead of the run method of A.