Question

如果通过writeMore()作为最后一个参数传递，则每次写入true的新行时，我都尝试写入文本文件。但是，作者继续写到同一第一行的末尾。我不明白问题是什么。

package FileIO;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class Buffered_Writer {

    public static void main(String[] args) throws IOException{

        String fileName = "myFile.txt";
        String message = "I'm written into the file.";

        File myFile = new File("C:\\Users\\User\\Desktop\\" + fileName);
        try {
            myFile.createNewFile();
        } catch (Exception e) {
            System.out.println("Could not create file!");
        }


        BufferedWriter writer = new BufferedWriter(new FileWriter(myFile, true));
        writer.write(message);

        writeMore("This much more has been written.", myFile, true);

        writer.close();
    }

    public static void writeMore(String message, File file, boolean newLine) throws IOException{

        BufferedWriter writer = new BufferedWriter(new FileWriter(file, true));
        if (newLine) {
            writer.append(" \n");
            writer.append(message);
        }
        else {
            writer.append(" " + message);
        }
        writer.close();
    }
}

Answer 1

为什么不使用正确的方法

https://docs.oracle.com/javase/7/docs/api/java/io/BufferedWriter.html#newLine()

根据javadocs

编写一个行分隔符。行分隔符字符串由系统属性line.separator，不一定是单个换行符（'\ n'）。

Answer 2

给予

File myFile = new File("C:\\Users\\User\\Desktop\\" + fileName);

我可以推断出您在Windows上。 Windows的行分隔符不是\n（它是\r\n，但不要对其进行硬编码）。请改用System.lineSeparator()。更改

writer.append(" \n");

到

writer.append(System.lineSeparator());

Answer 3

最好的解决方案是使用BufferedWriter.newLine()方法。此外，BufferedWriter应该正确关闭（使用try with resources）：

public static void writeMore(String message, File file, boolean newLine) throws IOException {
    try (BufferedWriter writer = new BufferedWriter(new FileWriter(file, true))) {
        if (newLine) {
            writer.newLine();
            writer.append(message);
        } else
            writer.append(" ").append(message);
    }
}

将新行添加到BufferedWriter

3 个答案: