CODEWITHSUNDEEP
javastringregexp-replace
Whimusical
Whimusical

Reputation: 6629

Getting capturing group programatically in replaceAll

I'd like to replace each occurrence of a regex within a string with a parsed $1. How can I do this?

    String line = "foo <<VAR>> bar <<VAR>>";
    Matcher matcher = Pattern.compile("<<(\\w*?)>>").matcher(line);
    Map<String,String> replacements = Collections.singletonMap("VAR","REPLACEMENT");
    String replacedLine = matcher.replaceAll(replacements.get(?.group(1)));
    Assert.assertTrue("foo REPLACEMENT bar REPLACEMENT".equals(replacedLine));

Upvotes: 0

Views: 50

Answers (2)

armnotstrong
armnotstrong

Reputation: 9065

Does this meet your need?

String line = "foo <<VAR>> bar <<VAR>>";

Map<String, String> replaceMap = new HashMap<>();
replaceMap.put("<<VAR>>", "REPLACEMENT");
//may be more replacement here

for(Map.Entry<String, String> entry: replaceMap.entrySet()){
    line = line.replaceAll(entry.getKey(), entry.getValue());
}

System.out.println(line); //<- foo REPLACEMENT bar REPLACEMENT

Upvotes: 1

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626689

You may use a Matcher#appendReplacement method to build the result "as you match":

String line = "foo <<VAR>> bar <<VAR>> in <<NO>>";
Matcher m = Pattern.compile("<<(\\w+)>>").matcher(line);
Map<String,String> replacements = Collections.singletonMap("VAR","REPLACEMENT");
StringBuffer replacedLine = new StringBuffer();
while (m.find()) {
    if (replacements.get(m.group(1)) != null)
        m.appendReplacement(replacedLine, replacements.get(m.group(1)));
    else
        m.appendReplacement(replacedLine, m.group());
}
m.appendTail(replacedLine);
System.out.println(replacedLine.toString()); // => foo REPLACEMENT bar REPLACEMENT in <<NO>>

See the Java demo.

Upvotes: 1

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