Which is the best way to escape the string when using split method in Java?

Question

I try to use Matcher.quoteReplacement, but I find it can escape $ but do not escape |. So I try to use the other method StringEscapeUtils.escapeJava, but it do not escape {. So I can only write a method like this. Does any java class already have this method?

String sampleStr="$abc.|{@#$abc";
String splitStr="{@#$"; 
System.out.println(Matcher.quoteReplacement(splitStr));
System.out.println(StringEscapeUtils.escapeJava(splitStr));
System.out.println(splitStr.replace("\\", "\\\\")
         .replace("*", "\\*")
         .replace("+", "\\+").replace("|", "\\|")
         .replace("{", "\\{").replace("}", "\\}")
         .replace("(", "\\(").replace(")", "\\)")
         .replace("^", "\\^").replace("$", "\\$")
         .replace("[", "\\[").replace("]", "\\]")
         .replace("?", "\\?").replace(",", "\\,")
         .replace(".", "\\.").replace("&", "\\&")); 

/* have exception when the split String contains "{"}
System.out.println(sampleStr.split(Matcher.quoteReplacement(splitStr)).length);
System.out.println(sampleStr.split(StringEscapeUtils.escapeJava(splitStr)).length);*/
System.out.println(sampleStr.split(splitStr.replace("\\", "\\\\")
         .replace("*", "\\*")
         .replace("+", "\\+").replace("|", "\\|")
         .replace("{", "\\{").replace("}", "\\}")
         .replace("(", "\\(").replace(")", "\\)")
         .replace("^", "\\^").replace("$", "\\$")
         .replace("[", "\\[").replace("]", "\\]")
         .replace("?", "\\?").replace(",", "\\,")
         .replace(".", "\\.").replace("&", "\\&")).length);

What is the expected output based on input `$abc.|{@#$abc` ? — Tim Biegeleisen, Feb 02 '21 at 02:27
Does this answer your question? [How to split String without regex](https://stackoverflow.com/questions/39038102/how-to-split-string-without-regex) — user202729, Feb 02 '21 at 02:32
@TimBiegeleisen,sampleStr.split(splitStr).length should be 2 — flower, Feb 02 '21 at 02:39
@flower (by the way, it's not recommended to only mention the question in the title. Better to repeat it in the question body) — user202729, Feb 02 '21 at 02:41
@flower Your comment doesn't answer the question, which is about what your output should be. — Tim Biegeleisen, Feb 02 '21 at 02:42

score 2 · Accepted Answer · answered Feb 02 '21 at 11:02

The method Matcher.quoteReplacement is, as the name suggests, for quoting a replacement string. When you want to quote a pattern string, you have to use Pattern.quote.

String sampleStr="$abc.|{@#$abc";
String splitStr="{@#$";
for(String s: sampleStr.split(Pattern.quote(splitStr)))
    System.out.println(s);

$abc.|
abc

Note that instead of converting a string to a quoted string, to let the regex engine convert it back to the literal string when parsing, you can tell the engine directly that you want to perform a literal match:

for(String s: Pattern.compile(splitStr, Pattern.LITERAL).split(sampleStr))
    System.out.println(s);

It’s a bit more to write but more efficient. Further, it works with arbitrary CharSequence inputs, not only with String.

Which is the best way to escape the string when using split method in Java?

1 Answers1