写入文件时插入换行符？

Question

So My code looks like this:

try {
    while ((line = br.readLine()) != null) {
        Matcher m = urlPattern.matcher (line);
        while (m.find()) {
            System.out.println(m.group(1));

            //the println puts linebreak after each find

            String filename= "page.txt";
            FileWriter fw = new FileWriter(filename,true);
            fw.write(m.group(1));
            fw.close();

            //the fw writes everything after each find with no line break
    }
}

I get right form of output at line System.out.println(m.group(1)); However when I later on want to write what is shown by m.group(1) It writes to file without putting linebreak since the code doesn't have one.

Answer 1

Just call fw.write(System.getProperty("line.separator")); .

System.getProperty("line.separator") will give you the line separator for your platform (whether Windows or some Unix flavor).

Answer 2

println(text) adds the line break to the string, and is essentially the same as print(text); print(System.getProperty("line.separator")); print(text); print(System.getProperty("line.separator")); .

So in order to add the line break you have to do the same.

However, to improve your code, I have two recommendations:

1. Don't create a new FileWriter in the loop. Create it outside the loop and close it after the loop.
2. Don't use a FileWriter , but instead a PrintWriter wrapped around a FileWriter . Then you get the same println() method as System.out .

Answer 3

just do

fw.write("\n");

that will put an escape character for a new line

Answer 4

您可以使用System.getProperty（“line.separator”）代替System.lineSeparator（）