Multi-threading is a Java feature that allows concurrent execution of two or more parts of a program. Each part of such program is called a thread. So, threads are light-weight processes within a process.
Threads can be created by using two mechanisms :
- Extending the Thread class
- Implementing the Runnable Interface
Thread creation by extending the Thread class
We create a class that extends the java.lang.Thread class. This class overrides the run() method available in the Thread class. A thread begins its life inside run() method. We create an object of our new class and call start() method to start the execution of a thread. Start() invokes the run() method on the Thread object.
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// Java code for thread creation by extending the Thread class class DemoMultithreading extends Thread { public void run() { try { // Displaying the thread that is running System.out.println ("Thread " + Thread.currentThread().getId() + " is running"); } catch (Exception e) { // Throwing an exception System.out.println ("Exception is caught"); } } } // Main Class public class Multithread { public static void main(String[] args) { int n = 8; // Number of threads for (int i=0; i<8; i++) { DemoMultithreading object = new DemoMultithreading(); object.start(); } } } |
Thread creation by implementing the Runnable Interface
We create a new class which implements java.lang.Runnable interface and override run() method. Then we instantiate a Thread object and call start() method on this object.
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// Java code for thread creation by implementing the Runnable Interface class DemoMultithreading implements Runnable { public void run() { try { // Displaying the thread that is running System.out.println ("Thread " + Thread.currentThread().getId() + " is running"); } catch (Exception e) { // Throwing an exception System.out.println ("Exception is caught"); } } } // Main Class class Multithread { public static void main(String[] args) { int n = 8; // Number of threads for (int i=0; i<8; i++) { Thread object = new Thread(new DemoMultithreading()); object.start(); } } } |