Java - 比较两个巨大的文本文件

Question

我正在尝试开发一个基本的java程序来比较两个巨大的文本文件并打印不匹配的记录。类似于SQL中的减号函数。但我没有得到预期的结果，因为即使两个文件相同，所有记录都会被打印。还建议我这种方法对于比较两个巨大的文本文件是否具有高效的性能。

import java.io.*;

public class CompareTwoFiles {
    static int count1 = 0 ;
    static int count2 = 0 ;

    static String arrayLines1[] = new String[countLines("\\Files_Comparison\\File1.txt")];
    static String arrayLines2[] = new String[countLines("\\Files_Comparison\\File2.txt")];

    public static void main(String args[]){  
        findDifference("\\Files_Comparison\\File1.txt","\\Files_Comparison\\File2.txt");
        displayRecords();
    }

    public static int countLines(String File){

        int lineCount = 0;
        try {
           BufferedReader br = new BufferedReader(new FileReader(File));
           while ((br.readLine()) != null) {
               lineCount++;
           }

       } catch (FileNotFoundException e) {
           e.printStackTrace();
       } catch (IOException e) {
           e.printStackTrace();
       }
           return lineCount;
    }

    public static void findDifference(String File1, String File2){
        String contents1 = null;  
        String contents2 = null; 
        try  
        {  
            FileReader file1 = new FileReader(File1);  
            FileReader file2 = new FileReader(File2);
            BufferedReader buf1 = new BufferedReader(file1); 
            BufferedReader buf2 = new BufferedReader(file2);

           while ((contents1 = buf1.readLine()) != null)  
            {  
               arrayLines1[count1] = contents1 ;
               count1++;
            }  

           while ((contents2 = buf2.readLine()) != null)  
            {  
               arrayLines2[count2] = contents2 ;
               count2++;
            }
       }catch (Exception e){
           e.printStackTrace();
       }
}



    public static void displayRecords() {      
        for (int i = 0 ; i < arrayLines1.length ; i++) {    
            String a = arrayLines1[i];  
            for (int j = 0; j < arrayLines2.length; j++){  
                String b = arrayLines2[j];  
                boolean result = a.contains(b);  
                   if(result == false){  
                       System.out.println(a);  
                   }  
            }

        }
    }
}

Answer 1

根据您的解释，您不需要嵌入循环

考虑

public static void displayRecords() { 

    for (int i = 0 ; i < arrayLines1.length && i < arrayLines2.length; i++) 
    {    
        String a = arrayLines1[i];  
        String b = arrayLines2[i];  

        if(!a.contains(b){  
               System.out.println(a);  
        }  
    }