Java.lang.ThreadGroup.checkAccess() Method

Description

The java.lang.ThreadGroup.checkAccess() method determines if the currently running thread has permission to modify this thread group.

Declaration

Following is the declaration for java.lang.ThreadGroup.checkAccess() method

public final void checkAccess()

Parameters

• NA

Return Value

This method does not return any value.

Exception

• SecurityException -- if the current thread is not allowed to access this thread group.

Example

The following example shows the usage of java.lang.ThreadGroup.checkAccess() method.

package com.tutorialspoint;

import java.lang.*;

public class ThreadGroupDemo implements Runnable
{
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.func();
   }

   public void func() {
      try {     
         // create a parent ThreadGroup
         ThreadGroup pGroup = new ThreadGroup("Parent ThreadGroup");
    
         // create a child ThreadGroup for parent ThreadGroup
         ThreadGroup cGroup = new ThreadGroup(pGroup, "Child ThreadGroup");

         // create a thread
         Thread t1 = new Thread(pGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread
         Thread t2 = new Thread(cGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();
            
         // checking the access for these ThreadGroups.
         try {
            pGroup.checkAccess();
            System.out.println(pGroup.getName() + " has access");
            cGroup.checkAccess();
            System.out.println(cGroup.getName() + " has access");
         }
            catch (SecurityException ex) {
               System.out.println("No access: " + ex.toString());
            }
         // block until the other threads finish
         t1.join();
         t2.join();
      }
      catch (InterruptedException ex) {
         System.out.println(ex.toString());
      }
   }

   // implements run()
   public void run() {

      for(int i=0;i<1000;i++) {
         i++;
      }
      System.out.println(Thread.currentThread().getName() + 
      " finished executing");
   }
} 

Let us compile and run the above program, this will produce the following result:

Starting Thread-0...
Starting Thread-1...
Parent ThreadGroup has access
Child ThreadGroup has access
Thread-0 finished executing
Thread-1 finished executing