Java 文本文件比较 - 多余和缺失

Question

我需要比较 2 个文本文件（MasterCopy.txt 和 ClientCopy.txt)。我想获取 ClientCopy.txt 中缺少的字符串列表。还需要获取超出的字符串列表。

MasterCopy.txt

的内容

伦敦
巴黎
罗马

ClientCopy.txt

的内容

伦敦
柏林
罗马
阿姆斯特丹

我想得到这些结果

缺失：

巴黎

过剩：

柏林
阿姆斯特丹

Answer 1

想到的两个想法是获取两个文件的差异：

https://code.google.com/p/java-diff-utils/

来自他们的 wiki

Task 1: Compute the difference between to files and print its deltas Solution:

import difflib.*;
public class BasicJavaApp_Task1 {
  // Helper method for get the file content
  private static List<String> fileToLines(String filename) {
    List<String> lines = new LinkedList<String>();
    String line = "";
    try {
      BufferedReader in = new BufferedReader(new FileReader(filename));
      while ((line = in.readLine()) != null) {
        lines.add(line);
      }
    } catch (IOException e) {
      e.printStackTrace();
    }
    return lines;
  }

  public static void main(String[] args) {
    List<String> original = fileToLines("originalFile.txt");
    List<String> revised  = fileToLines("revisedFile.xt");

    // Compute diff. Get the Patch object. Patch is the container for computed deltas.
    Patch patch = DiffUtils.diff(original, revised);

    for (Delta delta: patch.getDeltas()) {
      System.out.println(delta);
    }
  }
}

或使用哈希集：

http://docs.oracle.com/javase/7/docs/api/java/util/HashSet.html

修改@Nic的答案使用HashSet：

Scanner s = new Scanner(new File(“MasterCopy.txt”));
HashSet<String> masterlist = new HashSet<String>();
while (s.hasNext()){
  masterlist.put(s.next());
}
s.close();
s = new Scanner(new File(“ClientCopy.txt”));
HashSet<String> clientlist = new HashSet<String>();
while (s.hasNext()){
  clientlist.put(s.next());
}
s.close();

//Do the comparison
ArrayList<String> missing = new ArrayList<String>();
ArrayList<String> excess = new ArrayList<String>();
//Check for missing or excess
for(String line : masterlist){
    if(clientlist.get(line) == null) missing.add(line);
}
for(String line : clientlist){
    if(masterlist.get(line) == null) excess.add(line);
}

Answer 2

如果执行时间不是一个重要因素，您可以这样做，假设您只比较每一行：

//Get the files into lists
Scanner s = new Scanner(new File(“MasterCopy.txt”));
HashSet<String> masterlist = new HashSet<String>();
while (s.hasNext()){
    masterlist.add(s.next());
}
s.close();
s = new Scanner(new File(“ClientCopy.txt”));
HashSet<String> clientlist = new HashSet<String>();
while (s.hasNext()){
    clientlist.add(s.next());
}
s.close();

//Do the comparison
HashSet<String> missing = new HashSet<String>();
HashSet<String> excess = new HashSet<String>();
//Check for missing or excess
for(String s : masterlist){
    if(!clientlist.contains(s)) missing.add(s);
}
for(String s : clientlist){
    if(!masterlist.contains(s)) excess.add(s);
}

Java 文本文件比较 - 多余和缺失

Java Text File comparison - Excess and Missing

java

file

comparison