Example: Thread-specific data in Java programs

This example shows a Java™ program creating thread-specific data. Because a Java thread is created on an object, the use of thread-specific data is transparent. Java is a language that performs garbage collection. Note the lack of data destructors or other cleanup action.

Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.

/*
FileName: ATEST22.java
The output of this example is as follows:
 Entered the testcase
 Create/start threads
 Thread Thread-1: Entered
 Thread Thread-1: foo(), threadSpecific data=0 2
 Thread Thread-1: bar(), threadSpecific data=0 2
 Wait for the threads to complete
 Thread Thread-2: Entered
 Thread Thread-2: foo(), threadSpecific data=1 4
 Thread Thread-2: bar(), threadSpecific data=1 4
 Testcase completed
*/
import java.lang.*;
 
 
public class ATEST22 {
   public final static int NUMTHREADS = 2;
 
   static class theThread extends Thread {
      int               threadSpecific1;
      int               threadSpecific2;
 
      public theThread(int i, int i2) {
         threadSpecific1 = i;
         threadSpecific2 = i2;
      }
      public void run() {
         System.out.print("Thread " + getName() +
                          ": Entered\n");
         foo();
         return;
      }
      void foo() {
         System.out.print("Thread " + getName() +
                          ": foo(), threadSpecific data=" +
                          String.valueOf(threadSpecific1) + " " +
                          String.valueOf(threadSpecific2) + "\n");
         bar();
      }
      void bar() {
         System.out.print("Thread " + getName() +
                          ": bar(), threadSpecific data=" +
                          String.valueOf(threadSpecific1) + " " +
                          String.valueOf(threadSpecific2) + "\n");
      }
   }
 
   public static void main(String argv[]) {
      System.out.print("Entered the testcase\n");
 
      System.out.print("Create/start threads\n");
      theThread threads[] = new theThread[NUMTHREADS];
      for (int i=0; i <NUMTHREADS; ++i) {
 threads[i] = new theThread(i, (i+1)*2);
        threads[i].start();
      }
 
      System.out.print("Wait for the threads to complete\n");
      for (int i=0; i <NUMTHREADS; ++i) {
  try {
            threads[i].join();
         }
         catch (InterruptedException e) {
            System.out.print("Join interrupted\n");
         }
      }
      System.out.print("Testcase completed\nj");
      System.exit(0);
   }
 
}