Java/Development Class/CharacterIterator

Change the characters

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(); 
  }
}

Create an iterator on a substring (efgh)

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] argv) throws Exception {
    CharacterIterator it = new StringCharacterIterator("abcd");
    int begin = 5;
    int end = 9;
    int pos = 6;
    it = new StringCharacterIterator("abcd efgh ijkl", begin, end, pos);
    char ch = it.current();
    System.out.println(ch);
    ch = it.last();
    System.out.println(ch);
  }
}

Iterate a subset of a string

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] args) {
    String text = "this is a test";
    CharacterIterator it = new StringCharacterIterator(text, 4, 27, 5);
    for (char ch = it.first(); ch != CharacterIterator.DONE; ch = it.next()) {
      System.out.print(ch);
    }
  }
}

Iterate each characters of a string

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] args) {
    String text = "The quick brown fox jumps over the lazy dog";
    CharacterIterator it = new StringCharacterIterator(text);
    int vowels = 0;
    int consonants = 0;
    for (char ch = it.first(); ch != CharacterIterator.DONE; ch = it.next()) {
      if (ch == "a" || ch == "e" || ch == "i" || ch == "o" || ch == "u") {
        vowels = vowels + 1;
      } else if (ch != " ") {
        consonants = consonants + 1;
      }
    }
    System.out.println("Number of vowels: " + vowels);
    System.out.println("Number of consonants: " + consonants);
  }
}

Iterate over the characters in the backward direction

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] argv) throws Exception {
    CharacterIterator it = new StringCharacterIterator("abcd");
    for (char ch = it.last(); ch != CharacterIterator.DONE; ch = it.previous()) {
      System.out.println(ch);
    }
  }
}

Iterating the Characters of a String

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] argv) throws Exception {
    CharacterIterator it = new StringCharacterIterator("abcd");
    // Iterate over the characters in the forward direction
    for (char ch = it.first(); ch != CharacterIterator.DONE; ch = it.next()) {
      System.out.println(ch);
    }
  }
}

Reverse a string using CharacterIterator

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);
    }
  }
}

Use CharacterIterator to loop through a string

import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
public class Main {
  public static void main(String[] argv) throws Exception {
    CharacterIterator it = new StringCharacterIterator("abcd");
    char ch = it.first(); 
    ch = it.current(); 
    ch = it.next(); 
    ch = it.current(); 
    ch = it.last(); 
    int pos = it.getIndex(); 
    ch = it.next(); 
    pos = it.getIndex(); 
    ch = it.previous(); 
    ch = it.setIndex(1);
  }
}