Demonstrate thread priorities in Java

Rishi Raj

Answered on 19th Feb, 2019

A thread can be created by implementing the Runnable interface and overriding the run() method. Then a Thread object can be created and the start() method called.

The thread priority can be provided to the thread by the JVM or the programmer. It determines when the processor is provided to the thread as well as other resources. The method setPriority() of class Thread can be used to set the priority of the thread.

A program that demonstrates thread priorities in Java is given as follows:

Example

 Live Demo

public class ThreadDemo extends Thread {
   public void run() {
      System.out.println("Running...");
   }
   public static void main(String[] args) {
      ThreadDemo thread1 = new ThreadDemo();
      ThreadDemo thread2 = new ThreadDemo();
      ThreadDemo thread3 = new ThreadDemo();
      ThreadDemo thread4 = new ThreadDemo();
      ThreadDemo thread5 = new ThreadDemo();
      System.out.println("Default thread priority of Thread 1: " + thread1.getPriority());
      System.out.println("Default thread priority of Thread 2: " + thread2.getPriority());
      System.out.println("Default thread priority of Thread 3: " + thread3.getPriority());
      System.out.println("Default thread priority of Thread 4: " + thread4.getPriority());
      System.out.println("Default thread priority of Thread 5: " + thread5.getPriority());
      thread1.setPriority(8);
      thread2.setPriority(1);
      thread3.setPriority(6);
      thread4.setPriority(9);
      thread5.setPriority(3);
      System.out.println("Modified thread priority of Thread 1: " + thread1.getPriority());
      System.out.println("Modified thread priority of Thread 2: " + thread2.getPriority());
      System.out.println("Modified thread priority of Thread 3: " + thread3.getPriority());
      System.out.println("Modified thread priority of Thread 4: " + thread4.getPriority());
      System.out.println("Modified thread priority of Thread 5: " + thread5.getPriority());
      System.out.print(Thread.currentThread().getName());
      System.out.println("\nDefault thread priority of Main Thread: " + Thread.currentThread().getPriority());
      Thread.currentThread().setPriority(10);
      System.out.println("Modified thread priority of Main Thread: " + Thread.currentThread().getPriority());
   }
}

Output

Default thread priority of Thread 1: 5
Default thread priority of Thread 2: 5
Default thread priority of Thread 3: 5
Default thread priority of Thread 4: 5
Default thread priority of Thread 5: 5
Modified thread priority of Thread 1: 8
Modified thread priority of Thread 2: 1
Modified thread priority of Thread 3: 6
Modified thread priority of Thread 4: 9
Modified thread priority of Thread 5: 3
main
Default thread priority of Main Thread: 5
Modified thread priority of Main Thread: 10