ArrayBlockingQueue 对比Google Guava 非阻塞 EvictingQueue 示例

已发表: 2020-12-29
ArrayBlockingQueue 对比Google Guava 非阻塞 EvictingQueue 示例

并发实用程序在 Java 中非常棒。

java.util.concurrent 包包含许多实用程序，我们可以以多种不同的方式使用它们。

在本教程中，我们将讨论 java.util.concurrent 之间的区别。 ArrayBlockingQueue和 com.google.common.collect。 EvictingQueue 。

什么是驱逐队列？

EvictingQueue是Google's Guava library一部分。 这是一个non-blocking 、 bounded （固定大小）队列，当尝试将元素添加到full queue时，它会自动从队列head removes元素。

如何将 Google 的 Guava 库添加到您的 eclipse-java 项目中？

如果您使用的是 maven 项目，您可以将以下 maven 依赖项添加到 pom.xml 文件中。 如果non-maven项目——你必须从这里下载它并将库包含到你项目的类路径中。

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< dependency >
     < groupId > com . google . guava < / groupId >
     < artifactId > guava < / artifactId >
     < version > 30.1.1 - jre < / version >
< / dependency >

什么是 ArrayBlockingQueue？

它是一个blocking的、 bounded （固定大小）队列，将元素内部存储在一个数组中。 它CAN'T存储unlimited数量的元素。 此队列对元素进行FIFO （先进先出）排序。

Read more ：单例队列示例

让我们开始示例

  1. 创建大小为 10 的 ArrayBlockingQueue
  2. 创建大小为 10 的 EvictingQueue
  3. 尝试将 15 个元素添加到队列中
  4. 对于 EvictingQueue - 它不会抛出任何错误
  5. 对于 ArrayBlockingQueue——它会抛出Queue Full错误

创建类 CrunchifyArrayBlockingQueueVsEvictingQueue.java

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package crunchify . com . tutorials ;
 
import com . google . common . collect . EvictingQueue ;
 
import java . util . Queue ;
import java . util . concurrent . ArrayBlockingQueue ;
 
/**
* @author Crunchify.com
* ArrayBlockingQueue Vs. Google Guava Non-Blocking EvictingQueue Example
*
*/
 
public class CrunchifyArrayBlockingQueueVsEvictingQueue {
 
private static void CrunchifyArrayBlockingQueue ( ) {
// ArrayBlockingQueue: A bounded blocking queue backed by an array. This queue orders elements FIFO (first-in-first-out).
// The head of the queue is that element that has been on the queue the longest time.
// The tail of the queue is that element that has been on the queue the shortest time.
// New elements are inserted at the tail of the queue, and the queue retrieval operations obtain elements at the head of the queue.
ArrayBlockingQueue < String > crunchifyQueue = new ArrayBlockingQueue < String > (
10 ) ;
 
String crunchifyMsg = "This is ArrayBlockingQueue - by Crunchify" ;
try {
// We are looping for 15 times - Error once queue full
for ( int counter = 1 ; counter < = 15 ; counter ++ ) {
// add(): Inserts the specified element at the tail of this queue if it is possible to do so immediately without exceeding the queue's capacity,
// returning true upon success and throwing an IllegalStateException if this queue is full.
crunchifyQueue . add ( crunchifyMsg + counter ) ;
// size(): Returns the number of elements in this queue.
crunchifyLog ( "ArrayBlockingQueue size: " + crunchifyQueue . size ( ) ) ;
}
} catch ( Exception e ) {
crunchifyLog ( "\nException Occurred: " ) ;
e . printStackTrace ( ) ;
}
 
}
 
public static void main ( String [ ] args ) {
 
// Test EvictingQueue with size 10
CrunchifyEvictingQueue ( ) ;
 
crunchifyLog ( "\n============= New LINE ==============\n" ) ;
 
// Test ArrayBlockingQueue with size 10
CrunchifyArrayBlockingQueue ( ) ;
}
 
private static void CrunchifyEvictingQueue ( ) {
// Queue: A collection designed for holding elements prior to processing. Besides basic Collection operations,
// queues provide additional insertion, extraction, and inspection operations.
// Each of these methods exists in two forms: one throws an exception if the operation fails,
// the other returns a special value (either null or false, depending on the operation).
Queue < String > crunchifyQueue = EvictingQueue . create ( 10 ) ;
 
String crunchifyMsg = "This is EvictingQueue - by Crunchify" ;
try {
// We are looping for 15 times - No error after queue full.
// Instead, it will remove element from queue in FIFO order
for ( int i = 1 ; i < = 15 ; i ++ ) {
// add: Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions,
// returning true upon success and throwing an IllegalStateException if no space is currently available.
crunchifyQueue . add ( crunchifyMsg + i ) ;
 
crunchifyLog ( "EvictingQueue size: " + crunchifyQueue . size ( ) ) ;
}
} catch ( Exception e ) {
crunchifyLog ( "Exception Occurred: " + e ) ;
}
 
}
 
private static void crunchifyLog ( String crunchifyText ) {
System . out . println ( crunchifyText ) ;
 
}
 
}
 

只需在 Eclipse 控制台或 IntelliJ IDEA 中将这个 Java 程序作为应用程序运行，您就会看到这样的结果。

控制台结果：

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EvictingQueue size : 1
EvictingQueue size : 2
EvictingQueue size : 3
EvictingQueue size : 4
EvictingQueue size : 5
EvictingQueue size : 6
EvictingQueue size : 7
EvictingQueue size : 8
EvictingQueue size : 9
EvictingQueue size : 10
EvictingQueue size : 10
EvictingQueue size : 10
EvictingQueue size : 10
EvictingQueue size : 10
EvictingQueue size : 10
 
============= New LINE ==============
 
ArrayBlockingQueue size : 1
ArrayBlockingQueue size : 2
ArrayBlockingQueue size : 3
ArrayBlockingQueue size : 4
ArrayBlockingQueue size : 5
ArrayBlockingQueue size : 6
ArrayBlockingQueue size : 7
ArrayBlockingQueue size : 8
ArrayBlockingQueue size : 9
ArrayBlockingQueue size : 10
 
Exception Occurred :
java . lang . IllegalStateException : Queue full
at java . base / java . util . AbstractQueue . add ( AbstractQueue . java : 98 )
at java . base / java . util . concurrent . ArrayBlockingQueue . add ( ArrayBlockingQueue . java : 329 )
at crunchify . com . tutorials . CrunchifyArrayBlockingQueueVsEvictingQueue . CrunchifyArrayBlockingQueue ( CrunchifyArrayBlockingQueueVsEvictingQueue . java : 32 )
at crunchify . com . tutorials . CrunchifyArrayBlockingQueueVsEvictingQueue . main ( CrunchifyArrayBlockingQueueVsEvictingQueue . java : 52 )
 
Process finished with exit code 0

如果您在运行上述程序时遇到任何问题，请告诉我。