Java程序读取文本文件并删除重复的字符串并写入新的文本文件 [英] Java program to read text file and remove duplicate string and write new text file

问题描述

输入文件--- hello.txt文件

你好

java

你好

java

输出文件 - xyz.txt文件

你好

java



我尝试过：

input file---hello.txt file
hello
java
hello
java
output file--xyz.txt file
hello
java

What I have tried:

public static void main(String[] args) throws IOException 
    {
        // PrintWriter object for output.txt
        PrintWriter pw = new PrintWriter("output.txt");
         
        // BufferedReader object for input.txt
        BufferedReader br1 = new BufferedReader(new FileReader("input.txt"));
         
        String line1 = br1.readLine();
         
        // loop for each line of input.txt
        while(line1 != null)
        {
            boolean flag = false;
             
            // BufferedReader object for output.txt
            BufferedReader br2 = new BufferedReader(new FileReader("output.txt"));
             
            String line2 = br2.readLine();
             
            // loop for each line of output.txt
            while(line2 != null)
            {
                 
                if(line1.equals(line2))
                {
                    flag = true;
                    break;
                }
                 
                line2 = br2.readLine();
             
            }
             
            // if flag = false
            // write line of input.txt to output.txt
            if(!flag){
                pw.println(line1);
                 
                // flushing is important here
                pw.flush();
            }
             
            line1 = br1.readLine();
             
        }
         
        // closing resources
        br1.close();
        pw.close();
         
        System.out.println("File operation performed successfully");
    }
}

推荐答案

如果不需要双循环，Java有删除重复项的方法...

Java has means of removing duplicates, if double-loop isn't a requirement...

String[] szInput = {"input file---hello.txt file", "hello", "java", "hello", "java", "output file--xyz.txt file", "hello", "java"}; // you create it by reading all lines of the input file!!!
Set<String> szSet = new HashSet<String>(Arrays.asList(szInput)); // the same string will create the same hash so duplicates will be removed...
String[] szOutput = szSet.toArray(new String[szSet.size()]); // write to output file

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