package com.files;


interface MyList<e> {
    //sentinels
    public boolean isEmpty();
    public boolean isFull();
    public boolean addItem(e item);
    public boolean isItem(e item);
    public boolean removeItem(e item);
    public boolean insertAfter(e item, e newitem);
    public boolean insertBefore(e item, e newitem);
    public boolean updateItem(e item, e newitem);

}// end of interface

class MyListArray<E> implements MyList<E>{

    private int count;
    private int position;
    private E[] list;

    @SuppressWarnings("unchecked")
    public MyListArray(){
        this.list = (E[]) new Object[count];
    }

    @SuppressWarnings("unchecked")
    public MyListArray(int size) {
        this.list = (E[]) new Object[size];
    }

    @Override
    public boolean isEmpty() {  return count == 0;  }

    @Override
    public boolean isFull() {   return count == list.length;    }

    @Override
    public boolean addItem(E item) {
        if(!isEmpty()) {
            list[count] = item;
            count += 1;
        }
        return true;
    }

    @Override
    public boolean isItem(E item) {
        boolean found = false;
        for(int i=0; i<list.length; i++) {
            if(item.equals(list[i])) {
                found = true;
                position = i;
                break;
            }
        }
        return found;
    }

    @Override
    public boolean removeItem(E item) {
        boolean isElem = isItem(item);
        if(isElem) {
            for(int i=0; i<position; i++) {
                if(list[i] == item) {
                    list[i--] = null;
                }
            }
        }
        return isElem;
    }

    @Override
    public boolean insertAfter(E item, E newitem) {
        boolean isElem = isItem(item);
        if(isElem) {
            for(int i=0; i<list.length; i++) {
                if(position == i) {
                    list[i++] = newitem;
                }
            }
        }
        return isElem;
    }

    @Override
    public boolean insertBefore(E item, E newitem) {
        boolean isElem = isItem(item);
        if(isElem) {
            for(int i=0; i<list.length; i++) {
                if(position == i) {
                    list[++i] = newitem;
                }
            }
        }
        return isElem;
    }

    @Override
    public boolean updateItem(E item, E newitem) {
        boolean isElem = isItem(item);
        if(isElem) {
            for(int i=0; i<list.length; i++) {
                if(position == i) {
                    list[i] = newitem;
                }
            }
        }
        return isElem;
    }

    @Override
    public String toString() {
        StringBuffer sb = new StringBuffer();
        for(int i=0; i<list.length; i++) {
            if(list.length != 0)
                sb.append("->");
        }
        return sb.toString();
    }
}//End of the class

public class TestList {
    static public void main(String... args){
          MyList<String> list=new MyListArray<String>();
             list.addItem(new String("A"));
             list.addItem(new String("B"));
             list.addItem(new String("C"));
             list.addItem(new String("D"));
             list.addItem(new String("E"));
             System.out.println(list);
             System.out.println("Remove the item in the head:");
             list.removeItem(new String("A"));
             System.out.println(list);
             System.out.println("Insert a new  item after tail:");
             list.insertAfter(new String("E"),new String("X"));
             System.out.println(list);
             System.out.println("Insert a new  item after any item not the tail:");
             list.insertAfter(new String("B"),new String("X"));
             System.out.println(list);
             System.out.println("Insert a new  item before head:");
             list.insertBefore(new String("B"),new String("W"));
             System.out.println(list);
             System.out.println("Insert a new  item ebfore any item not the head:");
             list.insertBefore(new String("D"),new String("W"));
             System.out.println(list);
             System.out.println("Update element D, changed it to Y");
             list.updateItem(new String("D"),new String("Y"));
             System.out.println(list);
    }
}