accountwithoutsync.java

来自「java初学例子」· Java 代码 · 共 56 行

public class AccountWithoutSync {
  private Account account = new Account();
  private Thread[] thread = new Thread[100];

  public static void main(String[] args) {
    AccountWithoutSync test = new AccountWithoutSync();
    System.out.println("What is balance ? " +
      test.account.getBalance());
  }

  public AccountWithoutSync() {
    ThreadGroup g = new ThreadGroup("group");
    boolean done = false;

    // Create and launch 100 threads
    for (int i = 0; i < 100; i++) {
      thread[i] = new Thread(g, new AddAPennyThread(), "t");
      thread[i].start();
    }

    // Check if all the threads are finished
    while (!done)
      if (g.activeCount() == 0)
        done = true;
  }

  // A thread for adding a penny to the account
  class AddAPennyThread extends Thread {
    public void run() {
      account.deposit(1);
    }
  }

  // An inner class for account
  class Account {
    private int balance = 0;

    public int getBalance() {
      return balance;
    }

    public void deposit(int amount) {
      int newBalance = balance + amount;

      // This delay is deliberately added to magnify the
      // data-corruption problem and make it easy to see.
      try {
        Thread.sleep(5);
      }
      catch (InterruptedException ex) {
      }

      balance = newBalance;
    }
  }
}