Java - escaping double quotes in string from file

Question

I have html string from file. I need to escape all double quotes. So I do this way:

String content=readFile(file.getAbsolutePath(), StandardCharsets.UTF_8);
content=content.replaceAll("\"","\\\"");
System.out.println(content);

However, the double quotes are not escaped and the string is the same as it was before replaceAll method. When I do

String content=readFile(file.getAbsolutePath(), StandardCharsets.UTF_8);
content=content.replaceAll("\"","^^^");
System.out.println(content);

All double quotes are replaced with ^^^.

Why content.replaceAll("\"","\\\""); doesn't work?

Answer 1

It took me way too long in Java to discover Pattern.quote and Matcher.quoteReplacement. These will you achieve what you are trying to do here - which is a simple "find" and "replace" - without any regex and escape logic. The Pattern.quote here would not be necessary but it shows how you can ensure that the "find" part is not interpreted as a regex string:

@Test
public void testEscapeQuotes()
{
    String content="some content with \"quotes\".";
    content=content.replaceAll(Pattern.quote("\""), Matcher.quoteReplacement("\\\""));
    Assert.assertEquals("some content with \\\"quotes\\\".", content);
}

Remember that you can also use the simple .replace method which will also "replaceAll" but will not interpret your parameters as regular expressions:

@Test
public void testEscapeQuotes()
{
    String content="some content with \"quotes\".";
    content=content.replace("\"", "\\\"");
    Assert.assertEquals("some content with \\\"quotes\\\".", content);
}