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

Is there a built-in method? Not that I know of. However, it should be rather easy to do it yourself. Here's some completely untested code that should give you the basic idea:

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 getMatchingIndexes(List list, String regex) {
  ListIterator li = list.listIterator();

  List indexes = new ArrayList();

  while(li.hasNext()) {
    int i = li.nextIndex();
    String next = li.next();
    if(Pattern.matches(regex, next)) {
      indexes.add(i);
    }
  }

  return indexes;
}

I might have the usage of Pattern and ListIterator parts a bit wrong (I've never used either), but that should give the basic idea. You could also do a simple for loop instead of the while loop over the iterator.