How to get Thread Name in Runnable's run() method

Thread Names

When you create a Java thread you can give it a name. The name can help you distinguish different threads from each other. For instance, if multiple threads write to System.out it can be handy to see which thread wrote the text. Here is an example:

   Thread thread = new Thread("New Thread") {
      public void run(){
        System.out.println("run by: " + getName());
      }
   };
   thread.start();
   System.out.println(thread.getName());

Notice the string "New Thread" passed as parameter to the Thread constructor. This string is the name of the thread. The name can be obtained via the Thread's getName() method. You can also pass a name to a Thread when using a Runnable implementation. Here is how that looks:

   MyRunnable runnable = new MyRunnable();
   Thread thread = new Thread(runnable, "New Thread");
   thread.start();
   System.out.println(thread.getName());

Notice however, that since the MyRunnable class is not a subclass of Thread, it does not have access to the getName() method of the thread executing it. 

For example, you can't do it like this:

Runnable r = new Runnable(){
   public void run(){
      System.out.println( getName() + " running");  
      // you can't call getName() method here
   }; 
};

Thread.currentThread()

The Thread.currentThread() method returns a reference to the Thread instance executing currentThread() . This way you can get access to the Java Thread object representing the thread executing a given block of code. Here is an example of how to use Thread.currentThread() :

Thread thread = Thread.currentThread();

Once you have a reference to the Thread object, you can call methods on it. For instance, you can get the name of the thread currently executing the code like this:

   String threadName = Thread.currentThread().getName(); 

but you can get thread name like this:

Runnable r = new Runnable(){
   public void run(){
      System.out.println(Thread.currentThread().getName() + " running"); 
      // but you can get thread name like this      
   }; 
};

@reference_1_tutorials.jenkov.com
Creating and Starting Java Threads