백준 10828번 - 스택 (Java 8)

https://www.acmicpc.net/problem/10828

10828번: 스택

자료구조, 스택

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class Main {
    static List stack = new ArrayList();
    static StringTokenizer st;

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int numOfCase = Integer.parseInt(br.readLine());
        for(int i=0; i<numOfCase; i++){
            st = new StringTokenizer(br.readLine());
            readCommand(st.nextToken());
        }
    }
    public static void readCommand(String input){
        if (input.equals("push")) {
            int X = Integer.parseInt(st.nextToken());
            push(X);
        }
        if (input.equals("pop")) {
            pop();
        }
        if (input.equals("size")) {
            size();
        }
        if (input.equals("empty")) {
            empty();
        }
        if (input.equals("top")) {
            top();
        }
    }

    public static void push(int X){
        stack.add(X);
    }
    public static void pop(){
        if(stack.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(stack.remove(stack.size()-1));
        }
    }
    public static void size(){
        System.out.println(stack.size());
    }
    public static void empty(){
        if(stack.size() == 0){
            System.out.println(1);
        } else{
            System.out.println(0);
        }
    }
    public static void top(){
        if(stack.size() == 0){
            System.out.println(-1);
        } else{
            System.out.println(stack.get(stack.size()-1));
        }
    }
}