threadlocalexample.java

来自「java 完全探索的随书源码」· Java 代码 · 共 37 行

public class ThreadLocalExample extends Thread
{
  // Static instance for all threads to use
  private static MyThreadLocal theadLocal = new MyThreadLocal();
  // Holds which thread number this instance is. Used for display only
  private int threadCount = 0;

  // Default Constructor
  public ThreadLocalExample( String threadName, int threadCount )
  {
    super( threadName );
    this.threadCount = threadCount;
  }

  // Use a inner class to declare our new class
  static private class MyThreadLocal extends ThreadLocal
  {
    // If this is the first time the get or set is used,
    // this method will be called automatically
    protected Object initialValue()
    {
      // Initialize a new Double object
      return new Double (Math.random() * 1000.0);
    }
  }

  // Override the parents run method
  public void run()
  {
    // Print out the initial value for the ThreadLocal Object
    System.out.println( getName() + " - Initial Value: " + this.theadLocal.get() );
    // Change the value for this thread only
    this.theadLocal.set( new Integer( threadCount ) );
    // Print out the value, so that we can be sure that only our instance changed
    System.out.println( getName() + " - Current Value: " + this.theadLocal.get() );
  }
}