数组实现堆栈——Java实现

  1 package struct;
  2
  3
  4 //接口
  5 interface IArrayStack{
  6     //栈的容量
  7     int length();
  8     //栈中元素个数（栈大小）
  9     int size();
 10     //取栈顶元素
 11     Object top();
 12     //判断栈是否为空
 13     boolean isEmpty();
 14     //入栈
 15     Object pop();
 16     //出栈
 17     Object push(Object value);
 18     //清空栈
 19     void clear();
 20 }
 21
 22
 23 //实现接口的StackImpl类
 24 class StackImpl implements IArrayStack{
 25     static Object[] arr;//数组
 26     private int top;//标记栈顶位置，并且表示栈的容量大小
 27     private static int MAXSIZE = 10;//数组的最大长度(常量)
 28     //构造方法 
 29     public StackImpl(){
 30         arr = new Object[MAXSIZE];
 31         top = 0;
 32     }
 33     //求堆栈容量
 34     public int length() {
 35         return MAXSIZE;
 36     }
 37     //求堆栈中元素的个数，即堆栈大小
 38     public int size(){
 39         return top;
 40     }
 41     //取栈顶元素
 42     public Object top() {
 43         return arr[top];
 44     }
 45     //判断堆栈是否为空
 46     public boolean isEmpty() {
 47         return (size() == 0);
 48     }
 49     //出栈
 50     public Object pop() {
 51         if(isEmpty()){
 52             System.out.println("The Stack is empty");
 53             return -1;
 54         }
 55         Object value = arr[top - 1];
 56         top--;
 57         arr[top -1] = null;
 58         return value;
 59     }
 60     //对栈进行扩容（每次扩容一倍）
 61         public void expand(){
 62             Object[] largerArr = new Object[size()*2];
 63             for(int index = 0;index < top;index++){
 64                 largerArr[index] = arr[index];
 65             }
 66             arr = largerArr;
 67             MAXSIZE = arr.length;
 68         }
 69     //入栈
 70     public Object push(Object value) {
 71         //如果超过入栈元素数组长度
 72         if(top == arr.length){
 73             expand();
 74         }else{
 75             arr[top] = value;
 76             top++;
 77         }
 78         return arr;
 79     }
 80     //打印堆栈中元素
 81     public static void print(){
 82         myPrint1(arr);
 83     }
 84     private static void myPrint1(Object[] obj){
 85         for(int i = 0;i < obj.length;i++){
 86             System.out.println(obj[i] + " ");
 87         }
 88     }
 89     //清空堆栈
 90     public void clear() {
 91         for(int i = top;i > 0;i--){
 92             arr[i] = null;
 93             top--;
 94         }
 95     }
 96 }
 97
 98
 99 //测试函数
100 public class ArrayStack {
101     public static void main(String[] args) {
102         IArrayStack stack = new StackImpl();
103         System.out.println("==================栈中不存在元素测isEmpty函数================");
104         System.out.println(stack.isEmpty());
105         System.out.println("==================测length函数================");
106         System.out.println( stack.length());
107         System.out.println("==================测push及print函数================");
108         stack.push("lemon");
109         stack.push("hah");
110         stack.push(1);
111         stack.push(9);
112         stack.push("lemon");
113         stack.push("hah");
114         stack.push(1);
115         stack.push(9);
116         stack.push("lemon");
117         stack.push("hah");
118         stack.push(1);
119         stack.push(9);
120         StackImpl.print();
121         System.out.println("==================扩容后测length函数================");
122         System.out.println(stack.length());
123         System.out.println("==================测top函数================");
124         System.out.println(stack.top());
125         System.out.println("==================测size函数================");
126         System.out.println( stack.size());
127         System.out.println("==================测pop函数================");
128         stack.pop();
129         stack.pop();
130         System.out.println( stack.size());
131         System.out.println("==================栈中存在元素测isEmpty函数================");
132         System.out.println(stack.isEmpty());
133         System.out.println("==================clear后侧size函数================");
134         stack.clear();
135         System.out.println( stack.size());
136     }
137 }