Create a new line in Java's FileWriter

问题

I have coded the following FileWriter:

try {
    FileWriter writer = new FileWriter(new File(\"file.txt\"), false);

    String sizeX = jTextField1.getText();
    String sizeY = jTextField2.getText();
    writer.write(sizeX);
    writer.write(sizeY);

    writer.flush();
    writer.close();
} catch (IOException ex) {}

Now I want to insert a new line, just like you would do it with \\n normally, but it doesn\'t seem to work.

What can be done to solve this?

Thank you.

回答1:

If you want to get new line characters used in current OS like \r\n for Windows, you can get them by

• System.getProperty("line.separator");
• since Java7 System.lineSeparator()
• or as mentioned by Stewart generate them via String.format("%n");

---

You can also use PrintStream and its println method which will add OS dependent line separator at the end of your string automatically

PrintStream fileStream = new PrintStream(new File("file.txt"));
fileStream.println("your data");
//         ^^^^^^^ will add OS line separator after data 

(BTW System.out is also instance of PrintStream).

回答2:

Try System.getProperty( "line.separator" )

   writer.write(System.getProperty( "line.separator" ));

回答3:

Try wrapping your FileWriter in a BufferedWriter:

BufferedWriter bw = new BufferedWriter(writer);
bw.newLine();

Javadocs for BufferedWriter here.

回答4:

Since 1.8, I thought this might be an additional solution worth adding to the responses:

Path java.nio.file.Files.write(Path path, Iterable lines, OpenOption... options) throws IOException

StringBuilder sb = new StringBuilder();
sb.append(jTextField1.getText());
sb.append(jTextField2.getText());
sb.append(System.lineSeparator());
Files.write(Paths.get("file.txt"), sb.toString().getBytes());

If appending to the same file, perhaps use an Append flag with Files.write()

Files.write(Paths.get("file.txt"), sb.toString().getBytes(), StandardOpenOption.APPEND);

回答5:

Try:

String.format("%n");

See this question for more details.

回答6:

Here "\n" is also working fine. But the problem here lies in the text editor(probably notepad). Try to see the output with Wordpad.

回答7:

If you mean use the same code but add a new line so that when you add something to the file it will be on a new line. You can simply use BufferedWriter's newLine().
Here I have Improved you code also: NumberFormatException was unnecessary as nothing was being cast to a number data type, saving variables to use once also was.

try {
    BufferedWriter writer = new BufferedWriter(new FileWriter("file.txt"));
        writer.write(jTextField1.getText());
        writer.write(jTextField2.getText());
        writer.newLine();
        writer.flush();
        writer.close();
} catch (IOException ex) {
    System.out.println("File could not be created");
}

回答8:

I would tackle the problem like this:

    BufferedWriter output;
    output = new BufferedWriter(new FileWriter("file.txt", true));
    String sizeX = jTextField1.getText();
    String sizeY = jTextField2.getText();
    output.append(sizeX);
    output.append(sizeY);
    output.newLine();
    output.close();

The true in the FileWriter constructor allows to append.
The method newLine() is provided by BufferedWriter
Could be ok as solution?

来源：https://stackoverflow.com/questions/18549704/create-a-new-line-in-javas-filewriter