java顺序栈功能通过数组实现

1.定义栈接口

 1 public interface Stack<T> {
 2 //返回栈的大小
 3     public int size();
 4 //判断栈是否为空
 5     public boolean isEmpty();
 6 //入栈
 7     public void push(T t);
 8 //出栈
 9     public Object pop() throws StackEmptyException;
10 //返回栈顶元素
11     public Object peek() throws StackEmptyException ;
12 }

2.自定义异常

1 public class StackEmptyException extends RuntimeException {
2 //新增栈为空的异常类
3     public StackEmptyException(String eMeaasge ){
4         super(eMeaasge);
5     }
6 }

3.数组实现栈接口

 1 public class StackArray<T> implements Stack<T> {
 2 //栈的初始容量为2；
 3     private final int LEN=2;
 4 //    定义栈的指针；
 5     private int top;
 6 //    栈以数组实现
 7     private T[] elements;
 8 //    构造方法进行初始化
 9     public StackArray(){
10         top=-1;
11         elements= (T[]) new Object[LEN];
12     }
13 
14     @Override
15     public int size() {
16         return top+1;
17     }
18 
19     @Override
20     public boolean isEmpty() {
21         return top<0;
22     }
23 
24     @Override
25     public void push(T t) {
26         if(this.size()==elements.length){
27          this.expandSize();
28         }
29 //        ++top，先自增，再赋值
30          elements[++top]=t;
31     }
32 
33     @Override
34     public Object pop() throws StackEmptyException {
35         if(this.isEmpty()){
36             throw new StackEmptyException("当前栈为空，无法出栈");
37         }
38         Object obj = elements[top];
39 //        top--，先赋值，再自减
40         elements[top--]=null;
41         return obj ;
42     }
43 
44     @Override
45     public Object peek() throws StackEmptyException {
46         if(this.isEmpty()){
47             throw new StackEmptyException("当前栈为空，无内容");
48         }
49         return elements[top];
50     }
51 //栈容量扩容
52     public void expandSize(){
53         T[] a= (T[]) new Object[elements.length *2];
54         for(int i=0;i<elements.length;i++){
55             a[i]=elements[i];
56         }
57         elements=a;
58     }
59 }

4.测试

 1 public class Main {
 2 
 3     public static void main(String[] args) {
 4         StackArray<Integer> stackArray = new StackArray<Integer>();
 5         System.out.println(stackArray.size());
 6        /* stackArray.pop();*/
 7         stackArray.push(1);
 8         stackArray.push(2);
 9         stackArray.push(5);
10         stackArray.push(6);
11         System.out.println(stackArray.size());
12         System.out.println(stackArray.peek());
13 
14 
15     }
16 }

5.测试结果