List的安全复制

原创于 2011-05-19 15:03:55 发布 · 106 阅读

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#Java

本文介绍了一种使用Java实现的安全列表复制方法。通过演示如何创建同步列表并将其转换为字符串数组进行打印，展示了三种不同的安全复制技术：直接转换、同步块内的转换及同步条件下的类型转换。

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import java.util.ArrayList;   
import java.util.Collections;   
import java.util.List;   

public class SafeListCopy extends Object {   
  public static void printWords(String[] word) {   
    System.out.println("word.length=" + word.length);   
    for (int i = 0; i < word.length; i++) {   
      System.out.println("word[" + i + "]=" + word[i]);   
    }   
  }   

  public static void main(String[] args) {   
    List wordList = Collections.synchronizedList(new ArrayList());   

    wordList.add("Synchronization");   
    wordList.add("is");   
    wordList.add("important");   

    String[] wordA = (String[]) wordList.toArray(new String[0]);   

    printWords(wordA);   

    String[] wordB;   
    synchronized (wordList) {   
      int size = wordList.size();   
      wordB = new String[size];   
      wordList.toArray(wordB);   
    }   

    printWords(wordB);   

    // Third technique (the 'synchronized' *is* necessary)   
    String[] wordC;   
    synchronized (wordList) {   
      wordC = (String[]) wordList.toArray(new String[wordList.size()]);   
    }   

    printWords(wordC);   
  }   
}