用數組實現棧（Java）

特別簡單的寫了一下。

package ByteDance;

import java.util.EmptyStackException;

class Stack1 { //假設都是數字的插入
    private int[] nums = new int[2];
    private int size = 0; //記錄當前數組中利用的大小
    
    public void push(int num) {
        if(size == nums.length){
            resize();//對數組進行擴容
        }
        nums[size] = num;
        size++;
    }
    
    public int poll() {
        if(size < 0){
            throw new EmptyStackException();
        }
        int result =  nums[size-1];
        size--;
        return result;
    }
    
    public boolean isEmpty(){
    	return size==0;
    }
    
    
    
    public void printNums(){
    	for(int i=0;i<=size;i++) {
    		System.out.print(nums[i] + " ");
    	}
    }
    
    //擴容
    public void resize(){
        int length = 2*nums.length;
        int[] newnums =  new int[length];
        for(int i=0;i<nums.length;i++) {
            newnums[i] = nums[i];
        }
        nums = newnums;
    }
}

public class StackDemo {
	public static void main(String[] args) {
		Stack1 stack1 = new Stack1();
		stack1.push(2);
		stack1.push(3);
		stack1.push(4);
		
		
		stack1.printNums();
		System.out.println();
		System.out.println(stack1.poll());

	}

}