Java – join() method in Thread

join():

• An instance method belongs to Thread class.
• It stops the current the thread execution until joined thread execution completes.

For Example,

Consider First thread is calculating sum of first N numbers and second thread has to display the result. The Second thread has to wait until First thread completes calculation.

import java.util.Scanner; class Main {             static int n;             public static void main(String[] args)             {                         System.out.println(“***Sum of First N numbers***”);                         Scanner sc = new Scanner(System.in);                         System.out.print(“Enter n val : “);                         Main.n = sc.nextInt();                         Calc thread = new Calc();                         thread.start();                         try                         {                                     thread.join();                         }                         catch(Exception e)                         {                                     System.out.println(e.getMessage());                         }                         System.out.println(“Sum value : ” + Calc.sum);             } } class Calc extends Thread {             static int sum=0;             public void run()             {                         for (int i=1 ; i<=Main.n ; i++)                         {                                     Calc.sum = Calc.sum+i;                         }             } }