Wait() Example

[Phillipe Rodrigues]

Hi,
I tried an example for wait() after reading a tutorial.

The Example is as below:

package com.htras.application;
 
import java.util.*;
import java.io.*;
 

public  class TestApp extends Thread{
 

public static void main(String[] args){

Thread one =new Thread();
 
one.setName("First");
 

one.start();
try{
one.wait();
}catch(InterruptedException e){
e.getMessage();
}

}
public void run(){
System.out.println("Hello Mr. How R U");
}


}
 
   

On executing theabove I get the below error.

Exception in thread "main" java.lang.IllegalMonitorStateException: current thread not owner
at java.lang.Object.wait(Native Method)
at java.lang.Object.wait(Object.java:474)
at com.aciworldwide.application.TestApp.main(TestApp.java:19)


Where am I doing wrong.What does the error mean how can I correct it?

[amitabh mehra]

wait() must be called from within a synchronized context and a thread cannot invoke wait() on an object until it owns that object's lock.

[sarvesh meens]

* Thread should obtain the object's monitor before invoking wait() or notify() on it.
* Locks,synchronized blocks/methods are the techniques to acquire object monitor. Depending on application requirement,suitable technique should be adopted.
* wait() should always be matched with a notify(). If you get rid of java.lang.IllegalMonitorStateException in the above example by aquiring the object's(one) monitor,main-thread will wait for-ever.
* You may find this discussion helpful.
[ June 05, 2008: Message edited by: sarvesh meens ]

[Dawn Charangat]

should work correctly, if you put that wait call inside a synchronized block

[Nitesh Kant]

Hi Dawn,

It is generally not a good idea to WakeTheZombies
In all possibilities the original poster is not really waiting for inputs anymore!