The difference between run and start in thread class

Thread Class run and start The difference between

Let's first create a thread
Be careful ： What is used here is start start-up t Threads , And our code here is inherited Thread rewrite run How to write

class MyThread2 extends Thread {
    
    public void run() {
    
        while(true) {
    
            System.out.println("hello thread");
            try {
    
                sleep(1000);
            } catch (InterruptedException e) {
    
                e.printStackTrace();
            }
        }
    }
}
public class demo5 {
    
    public static void main(String[] args) {
    
        int a=0;
        Thread t= new MyThread2();
        t.start();
        while(true) {
    
            System.out.println("Hello");
        }
    }
}

After running , Use java Bring their own tools jconsole Check the progress ：

Look for the ！ At this time, there is a thread named Thread-0, This is the thread we created ourselves t.

Then we change the code just now , Change it to t.run();
And on again jconsole：

You will find that there is no thread we created in the thread
So we come to the following conclusion ：

1. Use start The thread can be started , Create a new thread , And will call internally Runnable Interface run Method
2. Use run No new threads will be created , Instead, we executed in the previous thread run Content rewritten inside