Java/Regular Expressions/Replace

Append Replacement Method

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static void main(String args[]) {
    Pattern p = Pattern.rupile("test");
    StringBuffer sb = new StringBuffer();
    String candidateString = "This is a test.";
    String replacement = "Test";
    Matcher matcher = p.matcher(candidateString);
    matcher.find();
    matcher.appendReplacement(sb, replacement);
  }
}

Escaping Special Characters in a Pattern

import java.util.regex.Pattern;
public class Main {
  public static void main(String[] argv) throws Exception {
    String patternStr = "i.e.";
    boolean matchFound = Pattern.matches(patternStr, "i.e.");
    matchFound = Pattern.matches(patternStr, "ibex"); 
    // Quote the pattern; i.e. surround with \Q and \E
    matchFound = Pattern.matches("\\Q" + patternStr + "\\E", "i.e."); 
    matchFound = Pattern.matches("\\Q" + patternStr + "\\E", "ibex"); 
    // Escape the pattern
    patternStr = escapeRE(patternStr);
    matchFound = Pattern.matches(patternStr, "i.e."); 
    matchFound = Pattern.matches(patternStr, "ibex"); 
    // Returns a pattern where all punctuation characters are escaped.
  }
  public static String escapeRE(String str) {
    Pattern escaper = Pattern.rupile("([^a-zA-z0-9])");
    return escaper.matcher(str).replaceAll("\\\\$1");
  }
}

REGEX = "a*b"

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import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class ReplaceDemo2 {
  private static String REGEX = "a*b";
  private static String INPUT = "aabfooaabfooabfoob";
  private static String REPLACE = "-";
  public static void main(String[] args) {
    Pattern p = Pattern.rupile(REGEX);
    Matcher m = p.matcher(INPUT); // get a matcher object
    INPUT = m.replaceAll(REPLACE);
    System.out.println(INPUT);
  }
}

Removing Line Termination Characters from a String

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static CharSequence removeLineTerminators(CharSequence inputStr) {
    String patternStr = "(?m)$^|[\\r\\n]+\\z";
    String replaceStr = " ";
    Pattern pattern = Pattern.rupile(patternStr);
    Matcher matcher = pattern.matcher(inputStr);
    return matcher.replaceAll(replaceStr);
  }
}

ReplaceAll Method from Matcher

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static void main(String args[]) {
    Pattern p = Pattern.rupile("(i|I)ce");
    String candidateString = "ice Ice Ice.";
    Matcher matcher = p.matcher(candidateString);
    String tmp = matcher.replaceAll("Java");
    System.out.println(tmp);
  }
}

replaceFirst Method from Matcher

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static void main(String args[]) {
    Pattern p = Pattern.rupile("(i|I)ce");
    String candidateString = "ice Ice Ice.";
    Matcher matcher = p.matcher(candidateString);
    String tmp = matcher.replaceFirst("Java");
    System.out.println(tmp);
  }
}

Working with Back References

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static void main(String args[]) {
    String regex = "(\\w)(\\d)(\\w+)";
    Pattern pattern = Pattern.rupile(regex);
    String candidate = "X99 ";
    Matcher matcher = pattern.matcher(candidate);
    String tmp = matcher.replaceAll("$33");
    System.out.println("REPLACEMENT: " + tmp);
    System.out.println("ORIGINAL: " + candidate);
  }
}