how thread can aquire more than one lock

[Shashank Sharma]

thread can enter a synchronized method, thus acquiring a lock, and then immediately invoke a synchronized method on a different object, thus acquiring that lock as well.

Above lines are taken from K& B page no708.

here author is talking about simultaneously obtaining a lock on " different object ",how do we re declare the same thread with a new runnable object.


please help me with this .please provide an example if any one can
thanks in advance

[Ireneusz Kordal]

How obtain many locks:

public class ManyLocks extends Thread {
    
    static Integer lock1 = new Integer(2);
    static Object lock2 = new Object();
    
    public void run(){ 
    // you may also use 'public void synchronized run()' to implicitely
    // synchronize on 'this' object
        synchronized(lock1){
            // ... code
            synchronized(lock2){
                // ... code
                synchronized(this){
                    // code ...
                }
            }
        }
    }
}

How declare thread using Runnable:

 
...
Runnable r = new Runnable(){
     public void run(){
       // ... code
     }
  };
Thread t1 = new Thread(r);
Thread t2 = new Thread(r);
t1.start();
t2.start();
...

Someone uses method with anonymous class that implements Runnable
- remember: Runnable is an interface, not a class!!!

 
Thread t = new Thread(
       new Runnable(){ 
            public void run(){
               //.. code
            }
       }
   ); // this is round bracket, not curly bracket !!
t.start();

And this also starts the Thread:

  new Thread( 
      new Runnable(){
          public void run(){ ... }
      }
  ).start();

[ August 06, 2008: Message edited by: Ireneusz Kordal ]