Java write escaped characters into file

Question

I'm writing to a file and I need to escape some characters like a quotation mark.

File fout = new File("output.txt");
try (FileOutputStream fos = new FileOutputStream(fout); BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(fos));) {
    String insert = "quote's";
    s += "'"+insert.replaceAll("'", "\\\'")+"'";
    bw.write(s.replaceAll("\r\n", "\\\r\\\n"));
    bw.newLine();
}

I'm trying to acheive writing 'quote\'s' to the file but it keeps removing the backslash and producing 'quote's'

I also want to write newlines into the file as the escaped character i.e instead of inserting a newline in file I want to write \r\n

Is this possible. I feel like I'm missing/forgetting something.

@shmosel that works! thanks. Care to detail an explanation ? — Ayo K
– Ayo K, Commented Nov 28, 2022 at 22:20
System.out.println("Hell'o, Wor'ld!".replaceAll("'", "\\\\'")); will print Hell\'o, Wor\'ld! — Popeye
– Popeye, Commented Nov 28, 2022 at 22:21
replaceAll handle regular expression. Including the replace part, as example System.out.println("Hello!".replaceAll("(ll)", "$1o$1")); this will result Hellollo! — Popeye
– Popeye, Commented Nov 28, 2022 at 22:27

shmosel · Accepted Answer · 2022-11-29 01:16:03Z

1

replaceAll() works with regex and accepts a special replacement syntax:

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string

You're not using regex, so you can use the plaintext replace() instead. And you only need 2 backslashes at a time:

s += "'"+insert.replace("'", "\\'")+"'";
bw.write(s.replace("\r\n", "\\r\\n"));

edited Nov 29, 2022 at 1:16

answered Nov 28, 2022 at 22:25

shmosel

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3 Comments

Popeye Over a year ago

you do not need "\\\'", instead use \\'

shmosel Over a year ago

That's true, single quotes don't have to be escaped.

ﾓｷｬﾃﾞ Over a year ago

OP says "instead of inserting a newline in file I want to write \r\n". But your code does not.

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