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run() Method in Java Thread

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  • Last Updated : 16 Nov, 2021

The run() method is available in the thread class constructed using a separate Runnable object. Otherwise, this method does nothing and returns. We can call the run() method multiple times. 

The run() method can be called in two ways which are as follows:

  1. Using the start() method.
  2. Using the run() method itself.

Syntax:

public void run()  
{    
    //statements  
}  

1. Using the start() method

We can use the start() method by using a thread object.

 Step 1: Create run method.

 Step 2: Create an object for the class.

Syntax: Usingstart obj=new Usingstart(); 

 Step 3: Create a thread object by passing the class variable.

Syntax: Thread t1 =new Thread(obj);    

 Step 4: This will call the run() method.

Syntax: t1.start();

Example:

Java




// Java program to demonstrate the working 
// of run() method using the start() method
  
public class Usingstart implements Runnable  
{    
    //run method
    public void run()  
    {    
        System.out.println("This thread is running");    
    }    
      
    //main method
    public static void main(String args[])  
    
        //create the object
        Usingstart obj=new Usingstart(); 
          
        //create thread object by passing the class variable
        Thread t1 =new Thread(obj);    
          
        // this will call run() method   
        t1.start();    
    }    
}


Output

This thread is running

2. Using the run() method

We can use the run() method by using a thread object.

Step 1: Create run method.

Step 2: Create an object for the class.

Syntax: Usingstart obj=new Usingstart();     

Step 3: This will call the run() method.

Syntax: obj.run();

Example:

Java




// Java program to demonstrate 
// the working of run() method
  
public class Usingstart implements Runnable  
{    
    //run method
    public void run()  
    {    
        System.out.println("This thread is running");    
    }    
      
    //main method
    public static void main(String args[])  
    
        //create the object
        Usingstart obj=new Usingstart(); 
             
        // this will call run() method   
        obj.run();    
    }    
}


Output

This thread is running

Calling run() Method Multiple Times 

In Java, we can also call the run() method multiple times. By using a for loop, we can call the same run method numerous times.

Example:

Java




// Java program to call the
// run() method multiple times
  
public class RumMultipleTimes extends Thread {
    public void run()
    {
        // run 10 times each
        for (int i = 1; i <= 10; i++) {
            System.out.println("Running " + i + " Time");
        }
    }
    
    public static void main(String args[])
    {
        // create object
        RumMultipleTimes t1 = new RumMultipleTimes();
  
        // call the run method
        t1.run();
        t1.run();
    }
}


Output

Running 1 Time
Running 2 Time
Running 3 Time
Running 4 Time
Running 5 Time
Running 6 Time
Running 7 Time
Running 8 Time
Running 9 Time
Running 10 Time
Running 1 Time
Running 2 Time
Running 3 Time
Running 4 Time
Running 5 Time
Running 6 Time
Running 7 Time
Running 8 Time
Running 9 Time
Running 10 Time

Overloading the run() Method

We can also overload the run()method. By changing the parameters, we can get exact things from the methods.

Example: Java program that takes two overloaded methods with one parameter and another with no parameters.

Here we first call the parameter method and then call the no parameter method.

Java




// Java Program to illustrate the behavior of
// run() method overloading
  
class GFG extends Thread {
  
    // run method with no parameters
    public void run()
    {
        System.out.println("no parameters method");
    }
  
    // run method with  parameters
    public void run(int i)
    {
        System.out.println("single parameter method");
    }
}
  
public class Test {
    public static void main(String[] args)
    {
        // create an object
        GFG t = new GFG();
  
        // call the parameter method
        t.run(8);
  
        // call the no parameter method
        t.run();
    }
}


Output

single parameter method
no parameters method

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