How do I use PriorityBlockingQueue class?

By Wayan in Concurrency 0 Comment

This example demonstrate how to use the PriorityBlockingQueue class. The PriorityBlockingQueue is one implementation of the BlockingQueue interface. It is an unbounded concurrent queue. The object place in this type of queue must implement the java.lang.Comparable interface. The Comparable interface defines how the order priority of the elements inside this queue.

For simplicity, in this example we use strings object as the elements to be placed in the queue. The String class implements the comparable interface. Running this example will print out the names in the string array in alphabetical orders.

package org.kodejava.util.concurrent;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;

public class PriorityBlockingQueueExample {
    public static void main(String[] args) {
        final String[] names =
                {"carol", "alice", "malory", "bob", "alex", "jacobs"};

        final BlockingQueue<String> queue = new PriorityBlockingQueue<>();

        new Thread(() -> {
            for (String name : names) {
                try {
                    queue.put(name);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "Producer").start();

        new Thread(() -> {
            try {
                for (int i = 0; i < names.length; i++) {
                    System.out.println(queue.take());
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }, "Consumer").start();
    }
}

This code print out:

alex
alice
bob
carol
jacobs
malory
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