/* * To change this template, choose Tools | Templates * and open the template in the editor. */ package arthur.datastruct.programe;
import java.util.Iterator; import java.util.NoSuchElementException;
/** * * @author dell */ public class MyListText implements Iterable {
private static final int DEFAULT_CAPACITY = 10; private int size; private Object[] items;
/** * clear the data in items */ public void clear() { for (int i = 0; i < items.length; i++) { items[i] = null; }
}
/** *return the size of MyList * @return int */ public int size() { return this.size; }
/** * to decide weather MyList is empty or not * @return boolean */ public boolean isEmpty() { return 0 == size; }
/** * get Object by id * @param id * @return */ public Object getObject(int id) { if (id >= this.size() || id < 0) { throw new ArrayIndexOutOfBoundsException(); }
return items[id]; }
public MyListText() { items = new Object[DEFAULT_CAPACITY]; }
@Override public Iterator iterator() { return new ListIterator(); }
/** * to update the data at number id in arraylist * @param id the number in arrayList * @param newObject the data you want to renew * @return */ public Object set(int id, Object newObject) { if (id >= this.size() || id < 0) { throw new ArrayIndexOutOfBoundsException(); }
Object oldObject = this.items[id]; items[id] = newObject;
return oldObject; }
/** * add new Object to items,before add we must make the space is enough, * if not ,double the items' space * @param object * @return */ public boolean add(Object object) {
//double the items' space if (size == items.length) { expandedLengthOfArray(items.length * 2); } items[size] = object; size++;
return true; }
/** * add a new data for items,before executing adddition,we,before * adding we must make the space is enough, * if not ,double the items' space * we should move * back the data,and the size should be ++ * @param id * @param object */ public void add(int id, Object object) { //double the space if items has no enough space if (items.length == this.size()) { this.expandedLengthOfArray(size * 2); } //move back data for (int i = this.size; i > id; i--) { items[i] = items[i - 1]; } items[id] = object; this.size++; }
/** * * to increase the length of array, * if the newCapacity is less than the size,then * this operation is not reasonable, else when executive this method, we must * Copy the original data to make sure the data are not lost * @param newCapacity */ public void expandedLengthOfArray(int newCapacity) { // copy data Object[] oldItems = this.items;
items = new Object[newCapacity];
System.arraycopy(oldItems, 0, items, 0, this.size); }
/** * remove the data at index position in items,we must make sure the data left * afther remove move forward,and the total number of size will be -- * @param index * @return */ public Object remove(int index) { Object removeObject = items[index]; for (int i = index; i < this.size(); i++) { items[i] = items[i + 1]; } this.size--; return removeObject; }
private class ListIterator implements Iterator {
private int index;
@Override public boolean hasNext() { return this.index < size(); }
@Override public Object next() { if (!this.hasNext()) { throw new NoSuchElementException(); } return items[index++]; }
@Override public void remove() { MyListText.this.remove(--index); } } }
