join() method – Java Thread class

join():

• join() is pre-defined method in Thread class.
• It is non static method hence we call on Thread object.
• Stop current thread execution until joined thread execution completed.

class Custom extends Thread
{
	public void run()
	{
		for (int i=1 ; i<=10 ; i++)
		{
			System.out.println("Custom : " + i);
			try{
				Thread.sleep(1000);
			}catch(InterruptedException e){ }
		}
	}
}
class Default 
{
	public static void main(String[] args) throws Exception
	{
		System.out.println("Starts @ Default thread");
		Custom t = new Custom();
		t.start();
		t.join();
		System.out.println("Ends @ Default thread");
	}
}

import java.util.Scanner ;
class Calculate extends Thread
{
	static int sum;
	public void run()
	{
		System.out.println("Calc starts...");
		Calculate.sum=0;
		for (int i=1 ; i<=SumOfN.n ; i++)
		{
			Calculate.sum = Calculate.sum+i;
		}
		System.out.println("Calc ends...");
	}
}
class SumOfN 
{
	static int n ;
	public static void main(String[] args) throws Exception
	{
		Scanner scan = new Scanner(System.in);
		System.out.println("Sum of First N numbers Code");

		System.out.print("Enter n val : ");
		SumOfN.n = scan.nextInt();

		Calculate calc = new Calculate();
		calc.start();

		calc.join();
		System.out.println("Sum value is : " + Calculate.sum);
	}
}