這裡定義了一個有界佇列 ,保證先進先出,在佇列達到上限時應該阻塞,直到佇列有元素被取出才能繼續往裡繼續新增 完整程式碼:

package com.comic.queue;

import java.util.LinkedList;
import java.util.concurrent.atomic.AtomicInteger;

public class BoundedQueue {
	// 佇列的最大值
	private int maxSize;
	// 計數器
	private AtomicInteger counter = new AtomicInteger(0);
	// 資料容器
	private LinkedList<Object> content = new LinkedList<Object>();
	// 瑣
	private Object lock = new Object();

	public BoundedQueue(int maxSize) {
		this.maxSize = maxSize;
	}

	/**
	 * 入佇列
	 * 
	 * @param obj
	 * @throws InterruptedException
	 */
	public void put(Object obj) throws InterruptedException {
		synchronized (lock) {
			while (maxSize == counter.get()) {
				System.out.println("佇列已滿,請等待....");
				lock.wait();
			}
			// 新增元素,計數,喚醒執行緒
			content.add(obj);
			counter.getAndIncrement();
			lock.notify();
			System.out.println(obj + "入列");
		}

	}

	/**
	 * 取
	 * 
	 * @return
	 * @throws InterruptedException
	 */
	public Object take() throws InterruptedException {
		Object obj = null;
		synchronized (lock) {
			while (0 == counter.get()) {
				System.out.println("佇列已空,請等待....");
				lock.wait();
			}
			// 獲取第一個元素,計數,喚醒執行緒
			obj = content.get(0);
			content.remove(0);
			counter.decrementAndGet();
			lock.notify();
		}
		return obj;
	}

	public static void main(String[] args) throws InterruptedException {
		final BoundedQueue queue = new BoundedQueue(5);
		queue.put("aa");
		queue.put("bb");
		queue.put("cc");
		queue.put("dd");
		queue.put("ff");
		Thread t = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					queue.put("gg");
					queue.put("hh");
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

			}
		}, "t1");
		t.start();
		
		Thread.sleep(500);
		System.out.println("**********************************");
		
		Thread t2 = new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					System.out.println("take:" + queue.take());
					System.out.println("take:" + queue.take());
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

			}
		}, "t2");
		t2.start();

	}

}
 

控制檯部分: aa入列 bb入列 cc入列 dd入列 ff入列 佇列已滿,請等待.... ********************************** take:aa gg入列 佇列已滿,請等待.... take:bb hh入列