Creating Threads in Java

[nahuel002]

Today in Java, I'm going to teach you how to create a program that will create threads. We all know that a thread is a basic processing unit in our computer to which an operating system allocates processor time, and more than one thread can be executing code inside a process. The Java Virtual Machine (JVM) allows an application to have multiple threads of execution running concurrently. Thus, threads have priority. It is just like a racing program.

So, now let's start this tutorial!

1. Open JCreator or NetBeans and make a java program with a file name of thread.java.

2. Import java.io package. Hence we will use an input/output in accessing files, with IOException.

1. import
   
   java.io.IOException
   
   ;
   

3. Provide a Thread extension in your classname and declare the following variables below.

1. class
   
   thread extends
   
   Thread
   
   {
   
2. private
   
   String
   
   carName;
   
3. private
   
   long
   
   aWhile;
   

4. Create a constructor named thread that is the same with the class name with the parameters of String carName, long delay. Make the delay variable equal to the aWhile variable that we have created above. Make the setDaemon equals to True. A daemon thread is also a thread, that does not prevent the Java Virtual Machine(JVM) from exiting when the program finishes but the thread is still running.

1. public
   
   thread(
   
   String
   
   carName, long
   
   delay)
   
   {
   
2. this
   
   .carName
   
   =
   
   carName;
   
3. aWhile =
   
   delay;
   
4. setDaemon(
   
   true
   
   )
   
   ;
   
5. }
   

5. Create a method named run for running the thread when using the start keyword. This will display the carnames and have a delay in displaying it.

1. public
   
   void
   
   run(
   
   )
   
   {
   
2. try
   
   {
   
3. while
   
   (
   
   true
   
   )
   
   {
   
4. System
   
   .out
   
   .print
   
   (
   
   carName)
   
   ;
   
5. sleep(
   
   aWhile)
   
   ;
   
6. 
   
7. }
   
8. }
   
   catch
   
   (
   
   InterruptedException
   
   e)
   
   {
   
9. System
   
   .out
   
   .println
   
   (
   
   carName +
   
   e)
   
   ;
   
10. }
    
11. }
    

6. In your Main, create three threads that have the carnames and the delay parameters.

1. public
   
   static
   
   void
   
   main(
   
   String
   
   [
   
   ]
   
   args)
   
   {
   
2. Thread
   
   first =
   
   new
   
   thread(
   
   "Toyota \n
   
   "
   
   , 100L)
   
   ;
   
3. Thread
   
   second =
   
   new
   
   thread(
   
   "Honda \n
   
   "
   
   , 200L)
   
   ;
   
4. Thread
   
   third =
   
   new
   
   thread(
   
   "Suzuki \n
   
   "
   
   , 500L)
   
   ;
   
5. System
   
   .out
   
   .println
   
   (
   
   "Press Enter when you have had enough...\n
   
   "
   
   )
   
   ;
   

To start running threads, put this code below.

1. first.start
   
   (
   
   )
   
   ;
   
2. second.start
   
   (
   
   )
   
   ;
   
3. third.start
   
   (
   
   )
   
   ;
   

To stop our thread from running, put this Try and Catch statement below. The thread will stop if we press Enter.

1. try
   
   {
   
2. System
   
   .in
   
   .read
   
   (
   
   )
   
   ;
   
3. System
   
   .out
   
   .println
   
   (
   
   "Enter pressed...\n
   
   "
   
   )
   
   ;
   
4. }
   
   catch
   
   (
   
   IOException
   
   e)
   
   {
   
5. System
   
   .out
   
   .println
   
   (
   
   e)
   
   ;
   
6. }
   

Full source code:

1. import
   
   java.io.IOException
   
   ;
   
2. 
   
3. class
   
   thread extends
   
   Thread
   
   {
   
4. 
   
5. private
   
   String
   
   carName;
   
6. private
   
   long
   
   aWhile;
   
7. 
   
8. 
   
9. public
   
   thread(
   
   String
   
   carName, long
   
   delay)
   
   {
   
10. this
    
    .carName
    
    =
    
    carName;
    
11. aWhile =
    
    delay;
    
12. setDaemon(
    
    true
    
    )
    
    ;
    
13. }
    
14. 
    
15. 
    
16. public
    
    void
    
    run(
    
    )
    
    {
    
17. try
    
    {
    
18. while
    
    (
    
    true
    
    )
    
    {
    
19. System
    
    .out
    
    .print
    
    (
    
    carName)
    
    ;
    
20. sleep(
    
    aWhile)
    
    ;
    
21. 
    
22. }
    
23. }
    
    catch
    
    (
    
    InterruptedException
    
    e)
    
    {
    
24. System
    
    .out
    
    .println
    
    (
    
    carName +
    
    e)
    
    ;
    
25. }
    
26. }
    
27. 
    
28. 
    
29. 
    
30. public
    
    static
    
    void
    
    main(
    
    String
    
    [
    
    ]
    
    args)
    
    {
    
31. Thread
    
    first =
    
    new
    
    thread(
    
    "Toyota \n
    
    "
    
    , 100L)
    
    ;
    
32. Thread
    
    second =
    
    new
    
    thread(
    
    "Honda \n
    
    "
    
    , 200L)
    
    ;
    
33. Thread
    
    third =
    
    new
    
    thread(
    
    "Suzuki \n
    
    "
    
    , 500L)
    
    ;
    
34. System
    
    .out
    
    .println
    
    (
    
    "Press Enter when you have had enough...\n
    
    "
    
    )
    
    ;
    
35. first.start
    
    (
    
    )
    
    ;
    
36. second.start
    
    (
    
    )
    
    ;
    
37. third.start
    
    (
    
    )
    
    ;
    
38. try
    
    {
    
39. System
    
    .in
    
    .read
    
    (
    
    )
    
    ;
    
40. System
    
    .out
    
    .println
    
    (
    
    "Enter pressed...\n
    
    "
    
    )
    
    ;
    
41. }
    
    catch
    
    (
    
    IOException
    
    e)
    
    {
    
42. System
    
    .out
    
    .println
    
    (
    
    e)
    
    ;
    
43. }
    
44. 
    
45. }
    
46. 
    
47. }
    

Output:

Best Regards,

Engr. Lyndon Bermoy
IT Instructor/System Developer/Android Developer/Freelance Programmer

If you have some queries, feel free to contact the number or e-mail below.
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