java用新行写到文件末尾

Question

I want to write results to the end of the file using java

FileWriter fStream;
        try {
            fStream = new FileWriter("recallPresision.txt", true);
            fStream.append("queryID=" + queryID + "         " + "recall=" + recall + "           Pres=" + presision);
            fStream.append("\n");
            fStream.flush();
            fStream.close();
        } catch (IOException ex) {
            Logger.getLogger(query.class.getName()).log(Level.SEVERE, null, ex);
        }

I put "\\n" in the statement , it writes to the file but not with new line

I want to print results with new line

Answer 1

The newline sequence is system dependent. On some systems its \\n , on others it's \\n\\r , \\r\\n , \\r or something else entirely different. Luckily, Java has a built in property which allows you to access it:

 String newline = System.getProperty("line.separator");

Answer 2

Wrong

fStream.append("\n");

Right

// don't guess the line separator!
fStream.append(System.getProperty("line.separator"));

Answer 3

It does print the newline, what you want is a blank line at the end. Add another \\n .

Answer 4

Try using \\r\\n instead.

Also, you should find that if you open your text file in a rich-text-editor, such as wordpad, your append has actually worked.

Edit: Ignore me. Jeffery and Andrew's answers are much better.

Answer 5

You could also change to:

fStream = new FileWriter("recallPresision.txt", true);
PrintWriter out = new PrintWriter(fStream);
out.println("queryID=" + queryID + "         " + "recall=" + recall + "           Pres=" + presision);
out.flush();
out.close();
fStream.close();