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我是 Java 新手（和 RoR 开发人员）。

我有一个简单的程序。球是共享的 amont 球员。球应传给随机球员。

好的，代码如下：

class Ball  {
    private int currentPlayer;

    public void setCurrentPlayer( int currentPlayer, int fromWho ) {
        this.currentPlayer = currentPlayer;
        System.out.println( "Ball:setCurrentPlayer " + fromWho + " ---> " + currentPlayer );
    }

    public int getCurrentPlayer() {
        return currentPlayer;
    }
}

class Player implements Runnable {
    private int myID;
    private Ball ball;
    private int playersCount;
    java.util.Random rnd;

    public Player(int id, Ball ball, int playersCount) {
        myID = id;
        this.ball = ball;
        this.playersCount = playersCount;
        rnd = new java.util.Random( id );
    }

    public void run() {
        int nextPlayer;
        while (true) {
            synchronized (ball) {
                if ( ball.getCurrentPlayer() == myID ) {
                    nextPlayer = rnd.nextInt(playersCount);
                    System.out.println( "Player nr. " + myID + " ---> " + nextPlayer );
                    ball.setCurrentPlayer( nextPlayer, myID );
                    ball.notifyAll();
                }  else {
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}

class Start {
    public static void main( String[] argv ) throws Exception {
        Ball p = new Ball();
        System.out.println("MAIN: ball will be in player: " + p.getCurrentPlayer());

        final int playersCount = 5;

        for ( int i = 0; i < playersCount; i++ ) {
            ( new Thread( new Player( i, p, playersCount ) ) ).start();
        }

        while ( true ) {
            Thread.sleep( 500 );
            System.out.println( "MAIN: ball is in player : " + p.getCurrentPlayer() );
        }
    }
}

但它不起作用。我得到例外：IllegalMonitorStateException。

我怎样才能解决这个问题？

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1 回答 1

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您正在等待this监视器而没有对其进行同步；你需要ball等待

于 2013-04-22T20:12:17.330 回答