Introduction

Until now, the programs we have discussed so far were sequential ones, i.e. each of the them has a beginning, an execution sequence, and an end. While the program is being executed, at any point of time, there is a single line of execution. One thing that you must note that a thread in itself is not a program, as it cannot run on its own. However it can be embedded with any other program.
A thread is a single sequential flow of control within a program.
There are many definition of thread some of the A thread is a lightweight process, a thread is a basic processing unit to which an operating system allocates processor time and more than one thread can be executing code inside a process.

States of thread

1-New-This is a state when a thread is not started. But the thread is created.
2-Runnable- This is the execution state of the thread.
3-Blocked- This is the state when a thread is waiting for a lock to access an object.
4-Waiting-In this state a thread is waiting indefinitely for another thread to perform an action.
5-Timed__Waiting. A state in which a thread is waiting for up to a specified period of time for another thread to perform an action.
6-Not Runnable- after Runnable states these three states are assumed to be in a not Runnable state. These three states are waiting, Timed_waiting and Terminated.
7-Terminated- In this state the thread is dead.

Life Cycle of a thread

thread2.jpg

Crating a thread

There are two ways for creating a thread.
Method-1 : By extend the Thread class of java.lang package.
Syntax
class MyThread extends Thread
{
-----------------;
-----------------;
}
The run( ) method has to be Overridden by writing codes required for the thread. The thread behaves as per this code segment.
public void run()
{
----------------;
----------------;
}
Example- In this Example we are going to create a thread with the help of the extends Thread class.
  1. class MyThread extends Thread
  2. {
  3. int i;
  4. MyThread(int i)
  5. {
  6. this.i=i;
  7. }
  8. public void run() //this method overrid from thread class
  9. {
  10. while(true)
  11. {
  12. System.out.println("abhishek kumar dubey:"+i++);
  13. try
  14. {
  15. Thread.sleep(1500); // use for break 1500 mili second
  16. }
  17. catch(InterruptedException e)
  18. {
  19. System.out.println(e);
  20. }
  21. if (i==15 ) // use for terminate the infinite loop
  22. {
  23. System.out.println(Thread.currentThread());
  24. break;
  25. }
  26. }
  27. }
  28. }
  29. public class TestThread
  30. {
  31. public static void main(String []args)
  32. {
  33. MyThread m1=new MyThread(1);
  34. m1.start(); // for start thread
  35. System.out.println(Thread.currentThread());
  36. }
  37. }
Output:
thread1.jpg
Method :2 By Implements Runnable Interface.
Note- If you make a thread by using Runnable Interface then it must override the run() method.
public MyThread implements Runnable {
-----------
-----------
public void run() {
------
------
}
}
Example-
  1. import java.lang.*;
  3. class Runner1 implements Runnable {
  4. int i;
  5. public void run() //this method overrid from Runnable interface must be,fuctionality as per reqairements
  6. {
  7. i = 0;
  8. while (true) {
  9. System.out.println("Runner_first" + i++);
  10. if (i == 10)
  11. break;
  12. }
  13. }
  14. }
  15. class Runner2 implements Runnable {
  16. int i;
  17. public void run() {
  18. i = 0;
  19. while (true) {
  21. System.out.println("Runner_second" + i++);
  22. if (i == 10)
  23. break;
  24. }
  25. }
  26. }
  27. public class ThreadDemo {
  28. public static void main(String[] args) {
  29. Runner1 r = new Runner1();
  30. Thread t = new Thread(r); // I M P
  31. /*from here run() method call which is override in Runner class*/
  32. t.start(); // for start thread 4 execution
  33. Runner2 r1 = new Runner2();
  34. Thread t1 = new Thread(r1);
  35. /*from here run() method call which is override in Runner class*/
  36. t1.start();
  37. }
  38. }
Output
runnable-thread

Summary

In this article, we learned about Threading in Java and creation of threads in our Java program.
Resource
A Complete MultiThreading Tutorial in Java
First Step to Java's Multithreading
Use of ByteStreams and CharacterStreams in JAVA
Learning JDBC (Java Database Connectivity)
Working with Hibernate - Display , Insert, Update and Delete in JAVA
Matrix Multiplication in Java