baekjoon 10828 스택 in java

baekjoon 10828 스택 in java**

스택 공부 필수 문제

[Java] 자바 Stack 클래스 사용법 & 예제 총정리

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.util.StringTokenizer;
 
public class Main {
 
	public static int[] stack;
	public static int size = 0;
 
 
	public static void main(String[] args) throws IOException {
 
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringBuilder sb = new StringBuilder();
		
		
		StringTokenizer st;
		
		int N = Integer.parseInt(br.readLine());
 
		stack = new int[N];
		
		while (N-- > 0) {
			st = new StringTokenizer(br.readLine(), " ");
 
			switch (st.nextToken()) {
			
			case "push":
				push(Integer.parseInt(st.nextToken()));
				break;
				
			case "pop":
				sb.append(pop()).append('\n');
				break;
				
			case "size":
				sb.append(size()).append('\n');
				break;
				
			case "empty":
				sb.append(empty()).append('\n');
				break;
				
			case "top":
				sb.append(top()).append('\n');
				break;
			}
 
		}
		System.out.println(sb);
	}
 
	public static void push(int item) {
		stack[size] = item;
		size++;
	}
	
	public static int pop() {
		if(size == 0) {
			return -1;
		}
		else {
			int res = stack[size - 1];
			stack[size - 1] = 0;
			size--;
			return res;
		}
	}
	
	public static int size() {
		return size;
	}
	
	public static int empty() {
		if(size == 0) {
			return 1;
		}
		else {
			return 0;
		}
	}
	
	public static int top() {
		if(size == 0) {
			return -1;
		}
		else {
			return stack[size - 1];
		}
	}
	
}