多線程生產者消費者問題

/**
 * 牛奶生產問題,冷庫中須要同時存放牛奶和發酵劑，因此固定讓牛奶數量不超過70份  發酵劑數量不超過30份
 */
public class Milk {
    private int MAX_NUM = 0;//存放牛奶
    private double MAX_NUM_MILK = 0;//存放發酵劑

    public synchronized void build(int i){//生產10份牛奶
        if(MAX_NUM < 70 && MAX_NUM_MILK >= 0.5){//只有當冷庫中的牛奶存量不大於70而且發酵劑數量大於1時生產
            System.out.println("生產了第" +(i+1)+ "份");
            MAX_NUM_MILK = MAX_NUM_MILK - 0.5;
            MAX_NUM = MAX_NUM + 1;
            this.notify();
        }else{
            try {
                this.wait();//庫存不足,不生產
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public synchronized void send(int i){//每次運輸一份牛奶
        if(MAX_NUM > 0){
            System.err.println("運輸了"+i+"份");
            MAX_NUM = MAX_NUM - 1;
            this.notify();
        }else{
            try {
                this.wait();//沒有存量,不運輸
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public synchronized void buildData(int i){
        System.err.println("CM:"+MAX_NUM_MILK);
        if(MAX_NUM_MILK < 30){
            System.err.println("生產了第"+i+"份發酵劑");
            MAX_NUM_MILK = MAX_NUM_MILK + 1;
            this.notify();
        }else{
            try {
                this.wait();//庫存容量不夠,不生產
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

public class Main {

    public static void main(String[] args) {
        Milk milk = new Milk();
        new Thread(new Runnable() {
            @Override
            public void run() {
                for(int i=0;i<50;i++){
                    milk.buildData(i);
                }
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                for(int i=0;i<100;i++){
                    milk.build(i);
                }
            }
        }).start();

        new Thread(new Runnable() {
            @Override
            public void run() {
                for(int i=0;i<100;i++){
                    milk.send(i+1);
                }
            }
        }).start();
}
}