Java Threads Tutorial 2 - How to Create Threads in Java by Extending Thread Class

In this Video I am going to give an How to Create Threads in Java by Extending Thread Class in Java.

Extending the Thread class includes following steps
- must implement the run() method
- thread ends when run() method finishes
- call .start() to get the thread ready to run

Threads is an Individual and separate unit of execution that is part of a process. multiple threads can work together to accomplish a common goal.Threads allow the program to run tasks in parallel. In many cases threads need to be synchronized,
that is, be kept not to handle the same data in memory concurrently. There are cases in which a thread needs to wait for another thread before proceeding

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[sunshine]

I think you can't say sleep() method is responsible for maintaining concurrency. With Sleep() you can delay thread. Here it's only a single println statement so you are able to show the concurrent result. Also if the processor is single-core then concurrency may work.
But suppose there are more statements in the run() method than only a println statement and execution time is greater than the sleep time. So suppose, thread1 finished execution and goes to sleep. thread2 starts running and as execution time is greater than sleep time, thread1 awakes starts printing its intermediate results (even thread2 is still running in another processor core). So here, thread1 is printing twice before thread2 even starts producing its result.

[alchavez]

Appreciate your simple explanation on calling start() and not run() in main class

[timdavids]

Thank you so much! I have been waiting a long time for you to touch upon the threading aspect of coding. Please continue the good work.

[sanjumaheeshan]

If anyone got a problem with numbers are not printing parallel, you have to use sleep() method inside the loop. And there is a good explanation why you can't see concurrency without using sleep() method in @Sunshine comment. Hope this might be a help

[lofts]

Great example for beginners, thank you @ProgrammingKnowledge

[ventjemazzel]

I included the sleep method in the for loop and that solved the problem for me

[AyushKumar-dkhm]

@ time 7:25 minute in video, the output sequence is : -
0
0
1
1
2
2
3
3
4
4
5 <---
6 <---
5 <---
6 <---
7 <---
8 <---
9 <---
7 <---
8 <---
9 <---
// these are the outputs there is difference on later stage

[ashwinibaburamamurthy]

thank u so much...u did an amazing job man!! thumbs up!!!

[farikaimutwira]

it was an awesome tutorial, Thank You

[ashwinkarki]

when i right click and goto source and goto override.implement method then there is no option like run() ...pl zhelp me

[fernandoluis]

You have not explained so many questions. At first why were the two threads printing parallel, then it prints concurrently. And when you added the sleep function why did it print parallel?

[GChris]

Love your accent, great video, thanks :))

[Technith]

Why priority was given to second thread when you used currentThread().getId()

[sundasqazi]

I want to write a program which make a new thread for accepting positive number from a main thread and then it displays all numbers from 0 to that number.. can u help me??

[yagzyalcntas]

when i define thread objects and run them in same order my output changes everytime i run the program?

[belaaaaastendemitteee]

How can I change the text of an JTextField in another Thread?

[vaneetkumar]

I am unable to run this thread class in my project and this is not visible in run configuration.

[mazenezzeddine]

Thanks,
Can it happen that each of these two threads run in parallel (not in concurrency) on two different cores of the system? How actually thread scheduling happens?

[Imtiaazs]

What is thread.sleep actually doing, please explain, ,

[PapaBubl]

Did you ever find the answer to "why did you lost concurrency at all when you first added currentThread().getID()? "