java - 如何从一个文件输入文本并输出到另一个文件

Question

我正在尝试从文本文件 input.txt 中获取字符串文本，并将相同的文本逐行输出到输出文件 output.txt

我试过这个：

public static void main(String[] args) throws NoSuchAlgorithmException, IOException {
    FileReader FR = new FileReader("C:\\FileLocation\\inputhashes.txt");
    BufferedReader BR = new BufferedReader(FR);
    PrintWriter PW = new PrintWriter("C:\\FileLocation\\outputtest.txt");
    for (int i = 0; i < 8 ; i++) {
        PW.println(BR.readLine());
    } 
}

但是这不起作用，我不确定为什么， outputtest.txt 文件完全是空的。

当我尝试

 System.out.println(BR.readLine());

控制台显示我期望的正确结果。

Answer 1

以下代码将内容从一个文件复制到另一个文件，正如@Robert Harvey 所述，您可能没有正确关闭文件。

        BufferedReader reader = Files.newBufferedReader(Paths.get("C:\\Users\\ngueno\\Desktop\\File 1.txt"));
        BufferedWriter writer = Files.newBufferedWriter(Paths.get("C:\\Users\\ngueno\\Desktop\\File 2.txt"), StandardOpenOption.WRITE);

        String line;

        while( (line = reader.readLine()) != null ) {
            writer.write(line);
        }

        reader.close();
        writer.flush();
        writer.close();

Answer 2

File inputFile = new File("inputFilePath");
File outputFile = new File("outputFilePath");

String output;
StringBuilder stringBuilder = new StringBuilder();

try (BufferedReader buffRead = new BufferedReader(new FileReader(inputFile))) {

    String line;
    while ( (line = buffRead.readLine()) != null) {
        stringBuilder.append(line + "\n");
    }
    output = stringBuilder.toString();
} catch (Exception e) {
    // handle exception
}

try (BufferedWriter buffWrite = new BufferedWriter(new FileWriter(outputFile))) {
    buffWrite.write(output);
} catch (Exception e) {
    // handle exception
}