關於棧實現

package 集合框架.stack;

public class Stack {
    //存放資料
    private int arr[];
    private  int top;
    //陣列容量
    private int capacity;
    Stack(int size){
        arr = new int[size];
        capacity = size;
        top =-1;
    }
    public void push(int value) {
        if (isFull()){
            System.out.println("溢位\n中止程式");
            System.exit(1);
        }
        arr[++top] = value;
        System.out.println("壓入元素"+value);
    }
    public int pop() {
        if (isEmpty()){
            System.out.println("陣列為空\n中止程式");
            //程式異常退出
            System.exit(1);
        }
        return arr[top--];
    }
    public boolean isFull() {
        return top == capacity - 1;
    }
    public boolean isEmpty(){
       return top == -1;
    }
    public void printStack() {
        for (int i = 0; i <= top; i++) {
            System.out.println(arr[i]);
        }
    }
    public static void main(String[] args) {
        Stack stack = new Stack(5);
        stack.push(1);
        stack.push(2);
        stack.push(3);
        stack.printStack();
        System.out.println("彈出");
        stack.pop();
        stack.printStack();
    }
}