implementing runnable instead of extends Thread

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implementing runnable instead of extends Thread

 
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  #1
Apr 24th, 2009
I the program I wish to run is a search for a number in 4 threads. Its working out fine and here is the code.
Java Syntax (Toggle Plain Text) 
  1. import java.lang.Math;
  2. import java.lang.Thread;
  3. public class NumberFinder
  4. {
  5.     public static void main(String args[])
  6.     {
  7.         int target = (int) (Math.random()*1000);
  8.         System.out.println("The number is " + target);
  9.  
  10.         Thread thread0 = new Finder(target, 0, 249);
  11.         Thread thread1 = new Finder(target, 250, 499);
  12.         Thread thread2 = new Finder(target, 500, 749);
  13.         Thread thread3 = new Finder(target, 750, 1000);
  14.         thread0.start();
  15.         thread1.start();
  16.         thread2.start();
  17.         thread3.start();
  18.     }
  19. }
  20.  
  21. class Finder extends Thread
  22. {
  23.  
  24.     int searchFor;
  25.     int beginRange;
  26.     int endRange;
  27.  
  28.  
  29.  
  30.     public Finder(int searchFor, int beginRange, int endRange)
  31.     {
  32.         this.searchFor = searchFor;
  33.         this.beginRange = beginRange;
  34.         this.endRange = endRange;
  35.         System.out.println ("in constructor " + this.getName() + " " + beginRange + " " + endRange);
  36.     }
  37.  
  38.  
  39.     public void run()
  40.     {
  41.         for (int i = beginRange; i < endRange; i++){
  42.  
  43.  
  44.             if (searchFor == i){
  45.  
  46.                 System.out.println("found at " +this.getName()+ " and the number is "+  i);
  47.             }
  48.  
  49.         }
  50.     }
  51. }

Now I wish to use Runnable instead of extends Thread

Java Syntax (Toggle Plain Text) 
  1. import java.lang.Math;
  2. import java.lang.Thread;
  3. public class NumberFinder
  4. {
  5.     public static void main(String args[])
  6.     {
  7.         int target = (int) (Math.random()*1000);
  8.         System.out.println("The number is " + target);
  9.  
  10.         Thread thread0 = new Finder(target, 0, 249);
  11.         Thread thread1 = new Finder(target, 250, 499);
  12.         Thread thread2 = new Finder(target, 500, 749);
  13.         Thread thread3 = new Finder(target, 750, 1000);
  14.         thread0.start();
  15.         thread1.start();
  16.         thread2.start();
  17.         thread3.start();
  18.     }
  19. }
  20.  
  21. class Finder implements Runnable
  22. {
  23.      Thread t = Thread.currentThread();
  24.     int searchFor;
  25.     int beginRange;
  26.     int endRange;
  27.  
  28.  
  29.  
  30.     public Finder(int searchFor, int beginRange, int endRange)
  31.     {
  32.         t.searchFor = searchFor;
  33.         t.beginRange = beginRange;
  34.         t.endRange = endRange;
  35.         System.out.println ("in constructor " + t.getName() + " " + beginRange + " " + endRange);
  36.     }
  37.  
  38.  
  39.     public void run()
  40.     {
  41.         for (int i = beginRange; i < endRange; i++){
  42.  
  43.  
  44.             if (searchFor == i){
  45.  
  46.                 System.out.println("found at " +this.getName()+ " and the number is "+  i);
  47.             }
  48.  
  49.         }
  50.     }
  51. }

But this code is not compiling. How to correct the code?
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Re: implementing runnable instead of extends Thread

 
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  #2
Apr 25th, 2009
Since Finder is no longer a subclass of thread, you cannot store a Thread reference to it. Use Thread thread0 = new Thread(new Finder(target, 0, 249));
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Re: implementing runnable instead of extends Thread

 
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  #3
Apr 25th, 2009
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Originally Posted by nmaillet View Post
Since Finder is no longer a subclass of thread, you cannot store a Thread reference to it. Use Thread thread0 = new Thread(new Finder(target, 0, 249));
Thanks a lot! that fixed it.
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Re: implementing runnable instead of extends Thread

 
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  #4
Apr 25th, 2009
I made a mistake I executed the old program by mistake.
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Re: implementing runnable instead of extends Thread

 
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  #5
Apr 25th, 2009
Java Syntax (Toggle Plain Text) 
  1. import java.lang.Math;
  2. import java.lang.Thread;
  3. public class NumberFinder
  4. {
  5.     public static void main(String args[])
  6.     {
  7.         int target = (int) (Math.random()*1000);
  8.         System.out.println("The number is " + target);
  9.         Thread t = Thread.currentThread();
  10.         Thread thread0 = new Thread(new Finder(target, 0, 250));
  11.         Thread thread1 = new Thread(new Finder(target, 251,500 ));
  12. 	Thread thread2 = new Thread(new Finder(target,501, 750));
  13. 	Thread thread3 = new Thread(new Finder(target,751, 1000));
  14.         thread0.start();
  15.         thread1.start();
  16.         thread2.start();
  17.         thread3.start();
  18.     }
  19. }
  20.  
  21. class Finder implements Runnable
  22. {
  23.  
  24.     int searchFor;
  25.     int beginRange;
  26.     int endRange;
  27.  
  28.  
  29.  
  30.     public Finder(int searchFor, int beginRange, int endRange)
  31.     {   Thread t = Thread.currentThread();
  32.         t.searchFor = searchFor;
  33.         t.beginRange = beginRange;
  34.         t.endRange = endRange;
  35.         System.out.println ("in constructor " + t.getName() + " " + beginRange + " " + endRange);
  36.     }
  37.  
  38.  
  39.     public void run()
  40.     {
  41.         for (int i = beginRange; i < endRange; i++){
  42.  
  43.  
  44.             if (searchFor == i){
  45.  
  46.                 System.out.println("found at " +t.getName()+ " and the number is "+  i);
  47.             }
  48.  
  49.         }
  50.     }
  51. }










Java Syntax (Toggle Plain Text) 
  1. C:\Users\>javac NumberFinder.java
  2. NumberFinder.java:32: cannot find symbol
  3. symbol  : variable searchFor
  4. location: class java.lang.Thread
  5.         t.searchFor = searchFor;
  6.          ^
  7. NumberFinder.java:33: cannot find symbol
  8. symbol  : variable beginRange
  9. location: class java.lang.Thread
  10.         t.beginRange = beginRange;
  11.          ^
  12. NumberFinder.java:34: cannot find symbol
  13. symbol  : variable endRange
  14. location: class java.lang.Thread
  15.         t.endRange = endRange;
  16.          ^
  17. NumberFinder.java:46: cannot find symbol
  18. symbol  : variable t
  19. location: class Finder
  20.                 System.out.println("found at " +t.getName()+ " and the number is
  21.  "+  i);
  22.                                                 ^
  23. 4 errors

Can somebody help me out here?
Last edited by grumpty; Apr 25th, 2009 at 4:09 am.
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Re: implementing runnable instead of extends Thread

 
0
  #6
Apr 25th, 2009
In method main write
java Syntax (Toggle Plain Text) 
  1. Finder thread0 = new Finder(target, 0, 249);//4x change type of Thread->Finder
In constructor Finder 4x change
java Syntax (Toggle Plain Text) 
  1. this.searchFor = searchFor; // change t. -> this.
Replace
java Syntax (Toggle Plain Text) 
  1.  Thread t = new Thread(this);//Thread.currentThread();
Write own method to start thread.
java Syntax (Toggle Plain Text) 
  1. //
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Re: implementing runnable instead of extends Thread

 
0
  #7
Apr 25th, 2009
Of course kind of view presented by nmaillet is good too.
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Use Thread thread0 = new Thread(new Finder(target, 0, 249));
In both cases you need
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In constructor Finder 4x change
this.searchFor = searchFor; // change t. -> this.
Inside main method line
java Syntax (Toggle Plain Text) 
  1. Thread t = Thread.currentThread();
is no needed.
Inside Finder constructor you don't need the line
java Syntax (Toggle Plain Text) 
  1. Thread t = Thread.currentThread();
In both println methods use simply static metod
java Syntax (Toggle Plain Text) 
  1. ... + Thread.currentThread().getName() + ...
to reflect actual (not stored) name of thread.
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