问题描述： 

ArrayList

问题分析： 

基本的实现

代码实现：

package c03;import java.util.Iterator;import static self.util.*;/** * @project: DataStructureAndAlgorithmAnalysis * @filename: MyArrayList.java * @version: 0.10 * @author: Jimmy Han * @date: 21:40 2015/7/13 * @comment: List implemented with Array * @result:*/public class MyArrayList
    
      implements Iterable
     
       {    private static final int DEFAULT_CAPACITY = 10;    private int theSize;    private AnyType[] theItems;    public MyArrayList(){doClear();}    public void clear(){doClear();}    private void doClear(){        theSize = 0; ensureCapacity(DEFAULT_CAPACITY);    }    public int size(){return theSize;}    public boolean isEmpty(){return size() == 0;}    public void trimToSize(){ensureCapacity(size());}    public AnyType get(int idx){        if(idx < 0 || idx >= size())            throw new ArrayIndexOutOfBoundsException();        return theItems[idx];    }    public AnyType set(int idx, AnyType newVal){        if(idx < 0 || idx >= size())            throw new ArrayIndexOutOfBoundsException();        AnyType old = theItems[idx];        theItems[idx] = newVal;        return old;    }    public void ensureCapacity(int newCapacity){        if(newCapacity < theSize)            return;        AnyType[] old = theItems;        theItems = (AnyType[]) new Object[newCapacity];        for(int i = 0; i < size(); i++)            theItems[i] = old[i];    }    public boolean add(AnyType x){        add(size(), x);        return true;    }    public void add(int idx, AnyType x){        if(theItems.length == size())            ensureCapacity(size()*2 + 1);        for(int i = theSize; i > idx; i--)            theItems[i] = theItems[i - 1];        theItems[idx] = x;        theSize++;    }    public AnyType remove(int idx){        AnyType removeItem = theItems[idx];        for(int i = idx; i < size() - 1; i++)            theItems[i] = theItems[i + 1];        theSize--;        return removeItem;    }    public Iterator
      
        iterator() {        return new ArrayListIterator();    }    private class ArrayListIterator implements java.util.Iterator
       
        {        private int current = 0;        public boolean hasNext(){            return current < size();        }        public AnyType next(){            if(!hasNext())                throw new java.util.NoSuchElementException();            return theItems[current++];        }        public void remove(){            MyArrayList.this.remove(--current);        }    }    public static void main(String[] args) {        MyArrayList
        
          marr = new MyArrayList
         
          ();        marr.add("www");        marr.add("bw");        marr.add(".com");        marr.add("s");        marr.remove(3);        marr.add(".cn");        self.util.printIterator(marr.iterator());        System.out.println(marr.get(2));        System.out.println(marr.set(1,"hello"));       self.util.printIterator(marr.iterator());    }}