阻塞队列
四组API
public class Test {
public static void main(String[] args) throws InterruptedException {
test4();
}
/**
* 抛出异常
*/
public static void test1(){
// 队列的大小
ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
System.out.println(blockingQueue.add("a"));
System.out.println(blockingQueue.add("b"));
System.out.println(blockingQueue.add("c"));
// IllegalStateException: Queue full 抛出异常!
// System.out.println(blockingQueue.add("d"));
System.out.println("=-===========");
System.out.println(blockingQueue.element()); // 查看队首元素是谁
System.out.println(blockingQueue.remove());
System.out.println(blockingQueue.remove());
System.out.println(blockingQueue.remove());
// java.util.NoSuchElementException 抛出异常!
// System.out.println(blockingQueue.remove());
}
/**
* 有返回值,没有异常
*/
public static void test2(){
// 队列的大小
ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
System.out.println(blockingQueue.offer("a"));
System.out.println(blockingQueue.offer("b"));
System.out.println(blockingQueue.offer("c"));
System.out.println(blockingQueue.peek());
// System.out.println(blockingQueue.offer("d")); // false 不抛出异常!
System.out.println("============================");
System.out.println(blockingQueue.poll());
System.out.println(blockingQueue.poll());
System.out.println(blockingQueue.poll());
System.out.println(blockingQueue.poll()); // null 不抛出异常!
}
/**
* 等待,阻塞(一直阻塞)
*/
public static void test3() throws InterruptedException {
// 队列的大小
ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
// 一直阻塞
blockingQueue.put("a");
blockingQueue.put("b");
blockingQueue.put("c");
// blockingQueue.put("d"); // 队列没有位置了,一直阻塞
System.out.println(blockingQueue.take());
System.out.println(blockingQueue.take());
System.out.println(blockingQueue.take());
System.out.println(blockingQueue.take()); // 没有这个元素,一直阻塞
}
/**
* 等待,阻塞(等待超时)
*/
public static void test4() throws InterruptedException {
// 队列的大小
ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);
blockingQueue.offer("a");
blockingQueue.offer("b");
blockingQueue.offer("c");
// blockingQueue.offer("d",2,TimeUnit.SECONDS); // 等待超过2秒就退出
System.out.println("===============");
System.out.println(blockingQueue.poll());
System.out.println(blockingQueue.poll());
System.out.println(blockingQueue.poll());
blockingQueue.poll(2,TimeUnit.SECONDS); // 等待超过2秒就退出
}
}
同步队列SynchronousQueue
- 没有容量,
- 进去一个元素,必须等待取出来之后,才能再往里面放一个元素!
- put、take
/**
* 同步队列
* 和其他的BlockingQueue 不一样, SynchronousQueue 不存储元素
* put了一个元素,必须从里面先take取出来,否则不能在put进去值!
*/
public class SynchronousQueueDemo {
public static void main(String[] args) {
BlockingQueue<String> blockingQueue = new SynchronousQueue<>(); // 同步队列
new Thread(()->{
try {
System.out.println(Thread.currentThread().getName()+" put 1");
blockingQueue.put("1");
System.out.println(Thread.currentThread().getName()+" put 2");
blockingQueue.put("2");
System.out.println(Thread.currentThread().getName()+" put 3");
blockingQueue.put("3");
} catch (InterruptedException e) {
e.printStackTrace();
}
},"T1").start();
new Thread(()->{
try {
TimeUnit.SECONDS.sleep(3);
System.out.println(Thread.currentThread().getName()+"=>"+blockingQueue.take());
TimeUnit.SECONDS.sleep(3);
System.out.println(Thread.currentThread().getName()+"=>"+blockingQueue.take());
TimeUnit.SECONDS.sleep(3);
System.out.println(Thread.currentThread().getName()+"=>"+blockingQueue.take());
} catch (InterruptedException e) {
e.printStackTrace();
}
},"T2").start();
}
}
视频参考https://www.bilibili.com/video/BV1B7411L7tE
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