clerk.java

非常好的java事例以及带源码事例的java2教程

import java.util.*;

public class Clerk implements Runnable
{
  Bank theBank;
  // The in-tray holding transactions
  private List inTray = Collections.synchronizedList(new LinkedList());

  private int maxTransactions = 8;      // Maximum transactions in the in-tray

  // Constructor
  public Clerk(Bank theBank)
  {
    this.theBank = theBank;                  // Who the clerk works for
    //inTray     = null;                //Commented out: don't need this now
  }

  // Receive a transaction
  synchronized public void doTransaction(Transaction transaction)
  {
    while(inTray.size() >= maxTransactions)
    try
    {
      wait();
    }
    catch(InterruptedException e)
    {
      System.out.println(e);
    }
    inTray.add(transaction);
    notifyAll();
  }

  // The working clerk...
  synchronized public void run()
  {
    while(true)
    {
      while(inTray.size() == 0)     // No transaction waiting?
        try
        {
          wait();                   // Then take a break until there is
        }
        catch(InterruptedException e)
        {
          System.out.println(e);
        }
      theBank.doTransaction((Transaction)inTray.remove(0));
      notifyAll();                  // Notify other threads locked on this clerk
    }
  }

  // Busy check 
  synchronized public void isBusy()
  {
    while(inTray.size() != 0)         // Is this object busy?
      try
      {
        wait();                       // Yes, so wait for notify call
      }
      catch(InterruptedException e)
      {
        System.out.println(e);
      }
    return;                           // It is free now
  }
}