Java实现泛型Stack-CPT102-Lab5

主要的难点在于：
　　1. 泛型的使用
　　2. 内存的动态开辟
　　3. 深度拷贝与浅拷贝的区别（line 30）
 1 package xxx.xxxxxxx;
 2 
 3 import java.util.EmptyStackException;
 4 
 5 public class ArrayStack<E> implements Cloneable {
 6 
 7     private E[] data;
 8     private int manyItems;
 9 
10     public ArrayStack() {
11         final int INITIAL_CAPACITY = 10;
12         manyItems = 0;
13         data = (E[]) new Object[INITIAL_CAPACITY];
14     }
15 
16     public ArrayStack(int initialCapacity) {
17         if (initialCapacity < 0)
18             throw new IllegalArgumentException("initialCapacity is negative: " + initialCapacity);
19         manyItems = 0;
20         data = (E[]) new Object[initialCapacity];
21     }
22 
23     public ArrayStack<E> clone() {
24         ArrayStack<E> copy;
25         try {
26             copy = (ArrayStack<E>) super.clone();
27         } catch (CloneNotSupportedException e) {
28             throw new RuntimeException("This class does not implement Cloneable");
29         }
30         copy.data = data.clone();
31         return copy;
32     }
33 
34     public void ensureCapacity(int minimumCapacity) {
35         E biggerArray[];
36         if (data.length < minimumCapacity) {
37             biggerArray = (E[]) new Object[minimumCapacity];
38             System.arraycopy(data, 0, biggerArray, 0, manyItems);
39             data = biggerArray;
40         }
41     }
42 
43     public int getCapacity() {
44         return data.length;
45     }
46 
47     public boolean isEmpty() {
48         return manyItems == 0;
49     }
50 
51     public E peek() {
52         if (manyItems == 0)
53             throw new EmptyStackException();
54         return data[manyItems - 1];
55     }
56 
57     public E pop() {
58         if (manyItems == 0)
59             throw new EmptyStackException();
60         return data[--manyItems];
61     }
62 
63     public void push(E e) {
64         if (manyItems == data.length)
65             ensureCapacity(manyItems * 2 + 1);
66         data[manyItems++] = e;
67     }
68 
69     public int size() {
70         return manyItems;
71     }
72 
73     public void trimToSize() {
74         E trimmedArray[];
75         if (data.length != manyItems) {
76             trimmedArray = (E[]) new Object[manyItems];
77             System.arraycopy(data, 0, trimmedArray, 0, manyItems);
78             data = trimmedArray;
79         }
80     }
81 
82     public int remainedCapacity() {
83         return data.length - manyItems;
84     }
85 }
~~Jason_liu O(∩_∩)O