THREAD:
*A thread is actually a lightweight process.
*Unlike many other computer languages, Java provides built-in support for multithreaded programming.
*A multithreaded program contains two or more parts that can run concurrently.
*Each part of such a program is called thread and each thread defines a separate path of execution.
*Thus, multithreading is a specialized form of multitasking.
Threads exist in several states.
New – When we create an instance of Thread class, a thread is in a new state.
Runnable – The Java thread is in running state.
Suspended – A running thread can be suspended, which temporarily suspends its activity. A suspended thread can then be resumed, allowing it to pick up where it left off.
Blocked – A java thread can be blocked when waiting for a resource.
Terminated – A thread can be terminated, which halts its execution immediately at any given time. Once a thread is terminated, it cannot be resumed.
Create a Thread by Implementing a Runnable Interface:
If your class is intended to be executed as a thread then you can achieve this by implementing a Runnable interface.
Step 1
As a first step, you need to implement a run() method provided by a Runnable interface. This method provides an entry point for the thread and you will put your complete business logic inside this method. Following is a simple syntax of the run() method −
public void run( )
Step 2
As a second step, you will instantiate a Thread object using the following constructor −
Thread(Runnable threadObj, String threadName);
Where, threadObj is an instance of a class that implements the Runnable interface and threadName is the name given to the new thread.
Step 3
Once a Thread object is created, you can start it by calling start() method, which executes a call to run( ) method. Following is a simple syntax of start() method −
void start();
Example:
Live Demo
class RunnableDemo implements Runnable {
private Thread t;
private String threadName;
RunnableDemo( String name) {
threadName = name;
System.out.println("Creating " + threadName );
}
public void run() {
System.out.println("Running " + threadName );
try {
for(int i = 4; i > 0; i--) {
System.out.println("Thread: " + threadName + ", " + i);
// Let the thread sleep for a while.
Thread.sleep(50);
}
} catch (InterruptedException e) {
System.out.println("Thread " + threadName + " interrupted.");
}
System.out.println("Thread " + threadName + " exiting.");
}
public void start () {
System.out.println("Starting " + threadName );
if (t == null) {
t = new Thread (this, threadName);
t.start ();
}
}
}
public class TestThread {
public static void main(String args[]) {
RunnableDemo R1 = new RunnableDemo( "Thread-1");
R1.start();
RunnableDemo R2 = new RunnableDemo( "Thread-2");
R2.start();
}
}
This will produce the following result −
