今天早上敲代碼時發現了好多問題，Xiao(RongQi r) {this.r = r;},這段代碼我一直搞不懂，既然上面已經private RongQi r，為什么還要多此一舉，其實創建Xiao對象時把RongQi 對象地址傳給this.r也就是private RongQi r的r這樣你調用put，get方法時就能找到RongQi對象。
多生產多消費要注意一個問題，等待喚醒機制是在判斷里面的，當一個生產者喚醒另外一個生產者時，沒有進行判斷就進行生產了，那么就會造成安全問題，所以將if語句換成while語句，喚醒語句要改成notifyAll，因為會出現生產與消費都在線程池里的現象。

class RongQi {
    private Object[] o = new Object[1];
    private Object obj = new Object();
    int num = 0;

    public void put(Object obj) {
        synchronized (obj) {
            while (o[0] != null) {
                try {
                    obj.wait();
                } catch (InterruptedException e) {

                }
                o[0] = obj+"--"+num;
                num++;
                System.out.println(Thread.currentThread().getName() + "生產者生產的---" +o[0]);
                obj.notifyAll();
            }

        }
    }

    public void get() {
        synchronized (obj) {
            while (o[0] == null) {
                try {
                    obj.wait();
                } catch (InterruptedException e) {

                }
                System.out.println(Thread.currentThread().getName() + "消費者消費的---" +o[0]);
                o[0]=null;
                obj.notifyAll();

            }
        }
    }
}

class Chan implements Runnable {
    private RongQi r;

    Chan(RongQi r) {
        this.r = r;
    }

    public void run() {
        while (true) {
            r.put("牛奶");
        }
    }
}

class Xiao implements Runnable {
    private RongQi r;

    Xiao(RongQi r) {
        this.r = r;
    }

    public void run() {
        while (true) {
            r.get();
        }
    }
}

class Demo1 {
    public static void main(String[] args) {
        RongQi r = new RongQi();
        Chan c = new Chan(r);
        Xiao x = new Xiao(r);
        Chan c1 = new Chan(r);
        Xiao x1 = new Xiao(r);
        Thread t = new Thread(c);
        Thread t2 = new Thread(c1);
        Thread t3 = new Thread(x);
        Thread t4 = new Thread(x1);
        t.start();
        t2.start();
        t3.start();
        t4.start();
    }
}