CustomContainer.java

package com.algorithm.demo.thread;

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

/**
 * 面试题
 * 写一个固定容量同步器，拥有put和get方法，以及getCount方法，能够支持2个胜场这线程及10个消费者线程的阻塞调用
 */

public class CustomContainer<T> {

    final private LinkedList<T> 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) {
                producer.await();
            }
            lists.add(t);
            ++count;
            consumer.signalAll();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }

    }

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

        return t;
    }

    public int getCount() {
        return count;
    }


    public static void main(String[] args) {
        CustomContainer<String> c = new CustomContainer<>();
        for (int i = 0; i < 10; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    for (int j = 0; j < 5; j++) {
                        System.out.println(c.get());
                    }
                }
            }, "c" + i).start();
        }
        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        for (int i = 0; i < 2; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    for (int j = 0; j < 25; j++) {
                        System.out.println(c.get());
                    }
                }
            }, "p" + i).start();
        }
    }
}