BlockingQueue four sets of APIs

Blocking queues

Under what circumstances will we use Blocking queues ？

Multithreading concurrent processing , Thread pool ！

Be sure to learn to use queues

add to 、 remove

BlockingQueue（ Blocking queues ） Four groups API

The way	Throw an exception	There is a return value , Don't throw exceptions	Block waiting	Overtime waiting
add to	add	offer	put	offer
remove	remove	poll	take	poll
First element of inspection team	element	peek	-	-

The first group ：（ Throw an exception ）

package bq;

import java.util.concurrent.ArrayBlockingQueue;

public class Test {
    
    public static void main(String[] args) {
    
        test1();
    }

    /** *  Throw an exception  */
    public static void test1(){
    
        // The size of the queue 
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue(3);

        System.out.println(blockingQueue.add("a"));
        System.out.println(blockingQueue.add("b"));
        System.out.println(blockingQueue.add("c"));

        // System.out.println(blockingQueue.element());// See who is the head of the team  
        
        // The queue is 3, We add a fourth element  ： IllegalStateException  Throw an exception ！（ Illegal status exception ）
        //System.out.println(blockingQueue.add("d"));
        System.out.println("----------------");
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());
        System.out.println(blockingQueue.remove());

        //NoSuchElementException  Throw an exception ！（ There is no such element exception ）
        //System.out.println(blockingQueue.remove());
    }
}

The second group （ There is a return value , Don't throw exceptions ）

package bq;

import java.util.concurrent.ArrayBlockingQueue;

public class Test {
    
    public static void main(String[] args) {
    
        test2();
    }

    /** *  There is a return value , Don't throw exceptions  */
    public static void test2(){
    
        // The size of the queue 
        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());// See who is the head of the team 
         
        //false  Don't throw exceptions ！
        //System.out.println(blockingQueue.offer("d"));

        System.out.println("----------------");
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        //null  Don't throw exceptions ！
        System.out.println(blockingQueue.poll());
    }
}

The third group （ Block waiting ）

package bq;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

public class Test {
    
    public static void main(String[] args) throws InterruptedException {
    
        test3();
    }

    /** *  wait for , Blocking （ Keep blocking ） */
    public static void test3() throws InterruptedException {
    
        // The size of the queue 
        ArrayBlockingQueue blockingQueue = new ArrayBlockingQueue<>(3);

        // Keep blocking 
        blockingQueue.put("a");
        blockingQueue.put("b");
        blockingQueue.put("c");
        //blockingQueue.put("d"); //  The queue has no place , Keep blocking 

        System.out.println(blockingQueue.take());
        System.out.println(blockingQueue.take());
        System.out.println(blockingQueue.take());
        //System.out.println(blockingQueue.take()); //  There is no such element , Keep blocking 
    }
}

Group 4 （ Overtime waiting ）

package bq;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;

public class Test {
    
    public static void main(String[] args) throws InterruptedException {
    
        test4();
    }

    /** *  wait for , Blocking （ Time out blocking ） */
    public static void test4() throws InterruptedException {
    
        // The size of the queue 
        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.offer("d", 2,TimeUnit.SECONDS));//  Wait more than 2 Seconds to exit 

        System.out.println("--------------");
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        System.out.println(blockingQueue.poll());
        //System.out.println(blockingQueue.poll(2, TimeUnit.SECONDS));//  Wait more than 2 Seconds to exit 
    }
}