面试题：生产者消费者模型

题目：写一个固定容量的同步容器，拥有put和get方法，一个getCount方法，能够支持2个生产者线程以及10个消费者现成的阻塞调用。

使用wait和notify/notifyAll来实现

import java.util.LinkedList;

public class MyContainer {
    final private LinkedList lists = new LinkedList();
    final private int MAX = 10;
    private int count = 0;

    public synchronized void put(T t) {
        while (lists.size() == MAX) {
            try {
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        lists.add(t);
        ++count;
        this.notifyAll();
    }

    public synchronized T get() {
        T t = null;
        while (lists.size() == 0) {
            try {
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        t = lists.removeFirst();
        --count;
        this.notifyAll();
        return t;
    }

    public static void main(String[] args) {
        MyContainer c = new MyContainer<>();
        //启动消费者线程
        for (int i = 0; i < 10; i++) {
            new Thread(() -> {
                for (int j = 0; j < 5; j++) {
                    System.out.println(c.get());
                }
            }, "c" + i).start();
        }
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        for (int i = 0; i < 2; i++) {
            new Thread(() -> {
                for (int j = 0; j < 25; j++) {
                    c.put(Thread.currentThread().getName() + " " + j);
                }
            }, "p" + i).start();
        }
    }
}

使用condition和signal实现

import java.util.LinkedList;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class MyContainer1 {
    final private LinkedList lists = new LinkedList();
    final private int MAX = 10;
    private int count = 0;

    private Lock lock = new ReentrantLock();
    private Condition producer = lock.newCondition();
    private Condition consumer = lock.newCondition();

    public void put(T t) {
        try {
            lock.lock();
            while (lists.size() == MAX){
                consumer.await();
            }
            lists.add(t);
            ++count;
            consumer.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }

    public synchronized T get() {
        T t = null;
        try {
            lock.lock();
            while (lists.size() == 0){
                consumer.await();
            }
            t = lists.removeFirst();
            --count;
            producer.signalAll();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
        return t;
    }

    public static void main(String[] args) {
        MyContainer c = new MyContainer<>();
        //启动消费者线程
        for (int i = 0; i < 10; i++) {
            new Thread(() -> {
                for (int j = 0; j < 5; j++) {
                    System.out.println(c.get());
                }
            }, "c" + i).start();
        }
        try {
            Thread.sleep(2000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        for (int i = 0; i < 2; i++) {
            new Thread(() -> {
                for (int j = 0; j < 25; j++) {
                    c.put(Thread.currentThread().getName() + " " + j);
                }
            }, "p" + i).start();
        }
    }
}