Search for a regexp in a java arraylist

Question

ArrayList  list = new ArrayList(); 
list.add(\"behold\");
list.add(\"bend\");
list.add(\"bet\");
list.add(\"bear\");
list.add(\"beat\");
list.add(\"bec         


        

Answer 1

Herms got the basics right. If you want the Strings and not the indexes then you can improve by using the Java 5 foreach loop:

import java.util.regex.Pattern;
import java.util.ListIterator;
import java.util.ArrayList;

/**
 * Finds the index of all entries in the list that matches the regex
 * @param list The list of strings to check
 * @param regex The regular expression to use
 * @return list containing the indexes of all matching entries
 */
List getMatchingStrings(List list, String regex) {

  ArrayList matches = new ArrayList();

  Pattern p = Pattern.compile(regex);

  for (String s:list) {
    if (p.matcher(s).matches()) {
      matches.add(s);
    }
  }

  return matches
}