No, you can not directly call run method to start a thread. You need to call start method to create a new thread.
If you call run method directly , it won’t create a new thread and it will be in same stack as main.
Lets understand with the help of example:
When you run above program , you will get below output:
As you can see when we are directly calling run method, it is not creating new threads.
If you call run method directly , it won’t create a new thread and it will be in same stack as main.
Lets understand with the help of example:
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package org.arpit.java2blog; class CustomThread extends Thread { public void run() { for (int i = 0; i < 5; i++) { try { Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Thread is running :"+i); } } } public class StartThreadAgainMain { public static void main(String[] args) { CustomThread ct1 = new CustomThread(); CustomThread ct2 = new CustomThread(); ct1.run(); ct2.run(); } } |
When you run above program , you will get below output:
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Thread is running :0 Thread is running :1 Thread is running :2 Thread is running :3 Thread is running :4 Thread is running :0 Thread is running :1 Thread is running :2 Thread is running :3 Thread is running :4 |
As you can see when we are directly calling run method, it is not creating new threads.
If you use start instead of run in above example:
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package org.arpit.java2blog; class CustomThread extends Thread { public void run() { for (int i = 0; i < 5; i++) { try { Thread.sleep(300); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Thread is running :"+i); } } } public class StartThreadAgainMain { public static void main(String[] args) { CustomThread ct1 = new CustomThread(); CustomThread ct2 = new CustomThread(); ct1.start(); ct2.start(); } } |
When you run above program , you will get below output:
Thread is running :0
Thread is running :0
Thread is running :1
Thread is running :1
Thread is running :2
Thread is running :2
Thread is running :3
Thread is running :3
Thread is running :4
Thread is running :4
Thread is running :0
Thread is running :1
Thread is running :1
Thread is running :2
Thread is running :2
Thread is running :3
Thread is running :3
Thread is running :4
Thread is running :4
You can not directly call run method to create a thread, you need to call start method to create a new thread.
You can go through core java interview questions for beginners and experienced for more such questions.
