The "Runnable" Interface - Creating Thread Objects with Runnable Objects

This section provides a tutorial example on how to create new threads with the 'Thread' class and runnable objects, which are created with classes that implements the 'Runnable' interface.

The second way to create a new thread is to:

Here is a tutorial sample program showing you how to do this:

class HelloRunnable implements Runnable {
   public static void main(String[] a) {
      HelloRunnable r = new HelloRunnable();
      Thread t = new Thread(r);
      t.start();
      System.out.println("Hello world! - From the main program."); 	
   }
   public void run() {
      System.out.println("Hello world! - From a thread.");
      try {
         Thread.sleep(1000*60*60);
      } catch (InterruptedException e) {
         System.out.println("Interrupted.");
      }
   }
}

Output:

Hello world! - From the main program.
Hello world! - From a thread.

Note that:

May be you are wondering why we need the second way of creating a new thread, which seems to be less straight forward than the first way? The answer is that Java classes can not be extended from two different base classes. So if you are in a situation where you want to create a new class by extending an existing class to inherit some nice features of that class, and you also want to make the new class executable as a thread, you have to use the second way to implement the "Runnable" interface in your new class.

Last update: 2014.

Table of Contents

 About This Book

 Installing JDK 1.8 on Windows

 Execution Process, Entry Point, Input and Output

 Primitive Data Types and Literals

 Bits, Bytes, Bitwise and Shift Operations

 Managing Bit Strings in Byte Arrays

 Reference Data Types and Variables

 StringBuffer - The String Buffer Class

 System Properties and Runtime Object Methods

 Generic Classes and Parameterized Types

 Generic Methods and Type Inference

 Lambda Expressions and Method References

Execution Threads and Multi-Threading Java Programs

 What Are Processes and Threads?

 The "Thread" Class - Creating Thread Objects With Thread Sub Classes

The "Runnable" Interface - Creating Thread Objects with Runnable Objects

 CPU Execution Time Shared by Multiple Threads

 CPU Execution Time Shared by Multiple Threads - Test Output

 Application Data Shared by Multiple Threads

 Application Data Shared by Multiple Threads - Test Results

 interrupt() - Method to Terminate Thread

 ThreadGroup Class and "system" ThreadGroup Tree

 Synchronization Technique and Synchronized Code Blocks

 Deadlock Condition Example Programs

 Garbage Collection and the gc() Method

 Outdated Tutorials

 References

 PDF Printing Version