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Introduction to Threads in Java

 Threads are basically a way to run multiple tasks concurrently this can be helpful to speed up your program, usually, a Java program runs on a single thread by utilizing only one core of your processor here the other processors are just sitting idly by introducing thread java helps us to make use of these idle processors. 

How to create a new thread process?

There are two ways of creating a new thread is by extending the Thread class and another way is by implementing Runnable interface either way the class must override the run method which will be called during the start method of the thread object. 

1. extending the Thread class 

public class Main extends Thread {
public void run() {
System.out.println("This code is running in a thread");
}
}

2.  Implementing Runnable Interface

public class Main implements Runnable {
public void run() {
System.out.println("This code is running in a thread");
}
}

The ideal way would be by implementing the Runnable interface because this enables us to extend other required base classes if required, here the method run() will be called after the thread is started, here you may call the methods which you wan to sublet or do any required process inside it, please note the run() which does returns nothing. 


Creating a thread Object.

    Creation of Thread object is same as creating any other object, Thread <name> = new Thread(<Object>) here a thread object will be created, now we can access the methods of the Thread class.

public class Main extends Thread {
public static void main(String[] args) {
Main thread = new Main();
}

public void run() {
System.out.println("This code is running in a thread");
}
}

How to start the thread ?

The thread can be called by calling start method which is available in the thread class, for example ThreadName.start() here when the start method is called the process will start and eventually it will automatically call the run method and the thread will become active and start processing the methods insde the run method.

public class Main extends Thread {
public static void main(String[] args) {
Main thread = new Main();
thread.start();
System.out.println("This code is outside of the thread");
}
public void run() {
System.out.println("This code is running in a thread");
}
}

LifeCycle of Thread

A thread exists only in any one of these state at a time, lets look at them one by one.

  • New

    as the same specifies this is a new state where the thread object is createes,but none of the code inside it not yet started to implement.

  • Runnable

    At this point the code inside this block is ready to run at any instant, once the thread scedualers flags greem the code inside it will start to implement one by one until there is any aburption.

  • Blocked
  • Waiting
  • Timed Waiting
  • Terminated

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