How to replace a string with another string using regex?

Question

INPUT TEXT FROM FILE :

someother block {
  enable route yes;
  dhcp auto;
  ....
}
options { 
  dnssec-enable yes;
  dnssec-validation yes;
  dnssec-lookaside auto;
 .....
}

I would like to replace all the "yes" and "auto" text in options block ONLY with "no" and "manual" respectively.

How can I accomplish this?

Here is my execution but the text is not replaced.

String dataPattern  = "\noptions \\{\\s*\n(dnssec-[a-z]+ ([a-z]+));";
Pattern filePattern = Pattern.compile(dataPattern, Pattern.DOTALL);
Matcher filePatternMatcher = filePattern.matcher(input);
if(filePatternMatcher.find()){
        System.out.println("0 - "+filePatternMatcher.group(0)); //0 - \ndnssec-enable yes;
        System.out.println("1 - "+filePatternMatcher.group(1)); //1 - dnssec-enable yes

        System.out.println("2 - "+filePatternMatcher.group(2)); //2 - yes
        String value = filePatternMatcher.group(2);
        value.replaceAll("\ndnssec-enable ([a-z]+);", "$1somethingelse");
        System.out.println("new replaced text:"+value); \\ new-replaced text: yes
}

Do you need regex for that? You could just string-replace yes; with no; and auto; with manual;. — Blorgbeard
– Blorgbeard, Commented Aug 30, 2016 at 3:08
I dont think its that simple. Since there can be multiple lines containing "yes" and "auto". The text provided at the top is read from a file. — Akh
– Akh, Commented Aug 30, 2016 at 3:10
I need to replace the yes and auto only if its within the matching options { block. — Akh
– Akh, Commented Aug 30, 2016 at 3:12
See Matcher.appendReplacement(). FYI: The reason your code is not working, is because String.replaceAll() returns the updated value. It does not modify the input string. Read the javadoc!! — Andreas
– Andreas, Commented Aug 30, 2016 at 3:14

Catenation · Accepted Answer · 2016-08-30 05:08:43Z

1

I think you could complete it with just Replace function!

    String test="someother block {" +
            "  enable route yes;" +
            "  dhcp auto;" +
            "  ...." +
            "}" +
            "options { " +
            "  dnssec-enable yes;" +
            "  dnssec-validation yes;" +
            "  dnssec-lookaside auto;" +
            " ....." +
            "}";

    String result;

    int opStartIndex=test.indexOf("options");
    int opEndIndex=opStartIndex+ test.substring(opStartIndex).indexOf("}");
    result=test.substring(0,opStartIndex)+test.substring(opStartIndex, opEndIndex).replace("yes","no").replace("auto","manual")+test.substring(opEndIndex);
    System.out.println(result);

answered Aug 30, 2016 at 5:08

Catenation

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