Exception in thread “main” java.lang.IllegalThreadStateException

Posted: May 9, 2012 in Java


It is child class of Runtime Exception and its is unchecked. It is raised programmatically when ever a method has invoked at illegal or in appropriate time.

Example 1:

After Starting a Thread we are not allowed to start the same thread again violation leads to illegalThreadStateException

public class Test extends Thread


public void run(){

System.out.println(“I am from run “);


public static void main(String[] args) {

Test test1 = new Test();

Thread thread = new Thread(test1);



}            }


I am from run Exception in thread “main”
at java.lang.Thread.start(Thread.java:595)
at com.clarity.test1.main(test1.java:108)



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