Java by API/java.text/StringCharacterIterator

new StringCharacterIterator(String text)

 

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  private static final String text = "this is a test";
  public static void main(String[] args) {
    CharacterIterator it = new StringCharacterIterator(text);
    for (char ch = it.last(); ch != CharacterIterator.DONE; ch = it.previous()) {
      System.out.print(ch);
    }
  }
}

StringCharacterIterator: setText(String text)

 
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] argv) throws Exception {
    CharacterIterator it = new StringCharacterIterator("abcd");
    ((StringCharacterIterator) it).setText("efgh");
    char ch = it.current(); 
  }
}