String.replaceAll（）问题

Question

I want to replace all exact matching of

 fm.get('Order# 

in a lengthy String with value

 fm.get('Order__'

i used syntax like :

    String calcStr = "return fm.get('Order#');";
    String fname = "Order#";
    String validfName = "Order__";

    String modifiedCalc1 = calcStr.replaceAll("fm.get('"+fname+"\\b", "fm.get('"+validfName);
    System.out.println(modifiedCalc1);

but i am getting pattern error.

    Exception in thread "main" java.util.regex.PatternSyntaxException:
    Unclosed group near index 18
    \bfm.get('Order#\b
              ^
at java.util.regex.Pattern.error(Unknown Source)
at java.util.regex.Pattern.accept(Unknown Source)

Answer 1

You need to escape the opening parenthesis and the point.

Remove also the \\b at the end for this specific case.

String modifiedCalc1 = calcStr.replaceAll("fm\\.get\\('"+fname, "fm.get('"+validfName);

Answer 2

If you want to replace a literal string using an API that expects a regular expression, you can use Pattern.quote (for the pattern side) and Matcher.quoteReplacement (for the substitution side):

calcStr.replaceAll(Pattern.quote("fm.get('Order#"),
                   Matcher.quoteReplacement("fm.get('Order__"));

Answer 3

It seems no regexp features are really needed in this case.

So plain string replacement can be used that is much more efficient:

String modifiedCalc1 = calcStr.replace("fm.get('"+fname, "fm.get('"+validfName);