Translated to Java (while making sure that the first character is upper case):

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;

public static String humanizeString( String source ) {
StringBuilder sb = new StringBuilder();
char last = ' ';
final StringCharacterIterator iterator = new StringCharacterIterator( source );
char c = Character.toUpperCase( iterator.current() );
while ( c != CharacterIterator.DONE ) {
if ( Character.isLowerCase( last ) && Character.isUpperCase( c ) ) {
sb.append( ' ' );
}
sb.append( c );
last = c;
c = iterator.next();
}
return sb.toString();
}

I did my own slightly different so that capitalized acronyms stay together, so UIUnlock becomes UI Unlock, for example.

http://www.darkhelmetlive.com/blog/2008/08/02/pascal-case-to-human-readable-with-csharp-extension-methods