TestEnumeration1.java

/*
    TestEnumeration1.java
    CIS 260
    2/16/2005
    David Klick

Demonstrates how you can create an Enumeration class
    for your own classes.
*/

import java.util.*;

public class TestEnumeration1 {
    public static void main(String[] args) {
        MyString s = new MyString("There once was a mighty sailing man");
        Enumeration e = s.characters();
        while (e.hasMoreElements())
            System.out.print(e.nextElement());
    }
}

class MyString {
    private String str;
   
    // creating new Strings is overkill, but I want
    //   to get you used to not sharing references
    //   to private variables
    MyString(String s) { str = new String(s); }
    String getString() { return new String(str); }
    public Enumeration characters() { return new Enum(); }

private class Enum implements Enumeration {
        private int pos = 0;

public boolean hasMoreElements() {
            return str.length() > pos;
        }

public Object nextElement() throws NoSuchElementException {
            if (!hasMoreElements()) throw new NoSuchElementException();
            else return new Character(str.charAt(pos++));
        }
    }
}