List.java

public class List {

    private static final int INITIAL_ARRAY_SIZE = 6;
    private static final char NULL_CHAR = '\u0000';
    private char[] mBackingStore;
    private int mLength;

    public List() {
       mBackingStore = new char[INITIAL_ARRAY_SIZE];
       mLength = 0;
    }
    
    public void removeAtIndex(int i) {
        // Assume index is in bounds
        
        // Compute the index of our last stored value
        int lastItemIndex = mLength - 1;

        // Replace the index to remove with the last item
        mBackingStore[i] = mBackingStore[lastItemIndex];

        // Set swap to null
        mBackingStore[lastItemIndex] = NULL_CHAR;

        // reduce the size
        mLength--;
    }

    public void insert(char c) {
        // Assume we are not full
        mBackingStore[mLength++] = c;
    }

    public String toString() {
        String list = "{ ";

        for (int i = 0; i < INITIAL_ARRAY_SIZE; i++) {
            char c = mBackingStore[i];
    
            if ( i == mLength ) {
                list += "| ";
            }

            if (mBackingStore[i] !=  NULL_CHAR) {
                list += "[" + c + "] ";
            } else {
                list += "[ ] ";
            }
        }

        list += "}";

        return list;
    }

    public static void main(String[] args) {

        // Lets make a list!
        char[] letters = new char[]{'X', 'Y', 'Z'};
        List list = new List();

        // And fill it with the letters
        for ( char letter : letters ) {
            list.insert(letter);
        }

        // Lets look at the list, remove at an index, and look at it again.
        System.out.println(list);

        list.removeAtIndex(1);

        System.out.println(list);

    }
}