What is use of Thread in Java code example

Example 1: java thread

public class ClassName extends Thread{
  public void run(){
    super.run();
    //Your Code
  }
}

public class Main{
  public static void main(String[] args){
    ClassName thread = new ClassName();
    thread.start();
  }
}

Example 2: java thread

public static void main(String[] args {
   ...
   Thread t1= new Thread(...);
   t1.start();
   ...
}

Example 3: creating thread in java example

class Multi3 implements Runnable{  
public void run(){  
System.out.println("thread is running...");  
}  
  
public static void main(String args[]){  
Multi3 m1=new Multi3();  
Thread t1 =new Thread(m1);  
t1.start();  
 }  
}