我如何合并文件 [英] how can i Merge files

问题描述

我该如何在包含在第二个文件中的第一个文件信息的开始处进行修改，以使它们彼此合并?请帮助，谢谢.

How can i wright in the beggining of the first file infomation which contains in second file, so that they merge each other?? please help, thanks.

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        FileInputStream fileReader = new FileInputStream(reader.readLine());
        FileOutputStream fileWriter = new FileOutputStream(reader.readLine(), true);
        while (fileReader.available() > 0) {
            int data = fileReader.read();
            fileWriter.write(data);
        }
        fileReader.close();
        fileWriter.close();
        reader.close();

推荐答案

这可以在纯Java中完成... 它读取第二个文件并追加到第一个文件.
请记住，这不适用于大文件，因为它将所有fileA内容保存到内存中.

This can be done in pure Java... It reads the second file and appends to the first file.
Keep in mind, that this will not work for large files, since it saves all of fileA content into memory.

Scanner reader = new Scanner(System.in);
System.out.println("Enter the first file path");
String fileA = reader.next();
System.out.println("Enter the second file path");
String fileB = reader.next();

try {

    // Read from and cache fileA
    StringBuilder cache = new StringBuilder();
    BufferedReader readerA = new BufferedReader(new FileReader(new File(fileA)));
    String line = null;
    while((line = readerA.readLine()) != null) {
        cache.append(line);cache.append("\n");
    }
    readerA.close();

    // Read from fileB and overwrite to fileA
    FileWriter writerB = new FileWriter(new File(fileA));
    BufferedReader readerB = new BufferedReader(new FileReader(new File(fileB)));
    line = null;
    while((line = readerB.readLine()) != null) {
        writerB.write(line);writerB.write("\n");
    }
    writerB.close();
    readerB.close();

    // Append original fileA content back into fileA
    FileWriter writerA = new FileWriter(new File(fileA), true);
    writerA.write(cache.toString());
    writerA.close();

} catch (Exception e) {
    e.printStackTrace();
}

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