Java 中使用多线程进行单词计数

2025 年 1 月 6 日 | 阅读 4 分钟

文本处理中的一个典型问题是计算单词数量。Java 的多线程可以通过将任务分解成更小的部分并同时处理它们来大大加快处理速度。在本节中，我们将讨论使用 Java 多线程进行单词计数的不同方法。

使用 Thread 类

在此方法中，我们将创建一个扩展 Thread 的自定义线程类。每个线程将处理一部分文本并计算单词。

文件名：WordCountUsingThread.java

import java.util.Arrays;
class WordCountThread extends Thread {
    private String[] words;
    private int start;
    private int end;
    private int wordCount;
    public WordCountThread(String[] words, int start, int end) {
        this.words = words;
        this.start = start;
        this.end = end;
    }
    public int getWordCount() {
        return wordCount;
    }
    @Override
    public void run() {
        wordCount = 0;
        for (int i = start; i < end; i++) {
            if (!words[i].isEmpty()) {
                wordCount++;
            }
        }
    }
}
public class WordCountUsingThread {
    public static void main(String[] args) {
        String text = "This is a sample text for word count using multithreading in Java.";
        String[] words = text.split("\\s+");
        int numberOfThreads = 4;
        WordCountThread[] threads = new WordCountThread[numberOfThreads];
        int wordsPerThread = words.length / numberOfThreads;
        for (int i = 0; i < numberOfThreads; i++) {
            int start = i * wordsPerThread;
            int end = (i + 1) * wordsPerThread;
            if (i == numberOfThreads - 1) {
                end = words.length;
            }
            threads[i] = new WordCountThread(words, start, end);
            threads[i].start();
        }
        int totalWordCount = 0;
        for (WordCountThread thread : threads) {
            try {
                thread.join();
                totalWordCount += thread.getWordCount();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("Total word count: " + totalWordCount);
    }
}

输出

Total word count: 12

使用 Runnable 接口

该方法使用 Runnable 接口创建线程。这是一种更灵活的方法，因为任何类都可以实现 Runnable 接口。

文件名：WordCountUsingRunnable.java

import java.util.Arrays;
class WordCountRunnable implements Runnable {
    private String[] words;
    private int start;
    private int end;
    private int wordCount;
    public WordCountRunnable(String[] words, int start, int end) {
        this.words = words;
        this.start = start;
        this.end = end;
    }
    public int getWordCount() {
        return wordCount;
    }
    @Override
    public void run() {
        wordCount = 0;
        for (int i = start; i < end; i++) {
            if (!words[i].isEmpty()) {
                wordCount++;
            }
        }
    }
}
public class WordCountUsingRunnable {
    public static void main(String[] args) {
        String text = "This is a sample text for word count using multithreading in Java.";
        String[] words = text.split("\\s+");
        int numberOfThreads = 4;
        Thread[] threads = new Thread[numberOfThreads];
        WordCountRunnable[] runnables = new WordCountRunnable[numberOfThreads];
        int wordsPerThread = words.length / numberOfThreads;
        for (int i = 0; i < numberOfThreads; i++) {
            int start = i * wordsPerThread;
            int end = (i + 1) * wordsPerThread;
            if (i == numberOfThreads - 1) {
                end = words.length;
            }
            runnables[i] = new WordCountRunnable(words, start, end);
            threads[i] = new Thread(runnables[i]);
            threads[i].start();
        }
        int totalWordCount = 0;
        for (int i = 0; i < numberOfThreads; i++) {
            try {
                threads[i].join();
                totalWordCount += runnables[i].getWordCount();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("Total word count: " + totalWordCount);
    }
}

输出

Total word count: 12

使用 ExecutorService

Java 中的 ExecutorService 框架提供了一种更高级别的替代方法来直接处理线程。它简化了线程管理并提高了可伸缩性。

文件名：WordCountUsingExecutorService.java

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.List;
import java.util.ArrayList;
class WordCountTask implements Callable<Integer> {
    private String[] words;
    private int start;
    private int end;
    public WordCountTask(String[] words, int start, int end) {
        this.words = words;
        this.start = start;
        this.end = end;
    }
    @Override
    public Integer call() {
        int wordCount = 0;
        for (int i = start; i < end; i++) {
            if (!words[i].isEmpty()) {
                wordCount++;
            }
        }
        return wordCount;
    }
}
public class WordCountUsingExecutorService {
    public static void main(String[] args) {
        String text = "This is a sample text for word count using multithreading in Java.";
        String[] words = text.split("\\s+");
        int numberOfThreads = 4;
        ExecutorService executorService = Executors.newFixedThreadPool(numberOfThreads);
        List<Future<Integer>> futures = new ArrayList<>();
        int wordsPerThread = words.length / numberOfThreads;
        for (int i = 0; i < numberOfThreads; i++) {
            int start = i * wordsPerThread;
            int end = (i + 1) * wordsPerThread;
            if (i == numberOfThreads - 1) {
                end = words.length;
            }
            WordCountTask task = new WordCountTask(words, start, end);
            futures.add(executorService.submit(task));
        }
        int totalWordCount = 0;
        for (Future<Integer> future : futures) {
            try {
                totalWordCount += future.get();
            } catch (InterruptedException | ExecutionException e) {
                e.printStackTrace();
            }
        }
        executorService.shutdown();
        System.out.println("Total word count: " + totalWordCount);
    }
}

输出

Total word count: 12

结论

多线程可以极大地提高单词计数操作的效率，特别是对于长文本。ExecutorService 提供了更灵活和可伸缩的解决方案，而 Thread 和 Runnable 类提供了更基础的方法。每种方法都有其用例集，可以根据应用程序的特定需求进行选择。

下一主题Java 中可以将主线程设置为守护线程吗？

Java 中使用多线程进行单词计数

使用 Thread 类

使用 Runnable 接口

使用 ExecutorService

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Java 中使用多线程进行单词计数

使用 Thread 类

使用 Runnable 接口

使用 ExecutorService

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