[JAVA] 이칙(+,-) 계산기

이칙(+,-) 계산기

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package Test1;

 

import java.util.LinkedList;

import java.util.Queue;

import java.util.Scanner;

 

public class Calculator {

    public static void main(String[] args) {

 

        Scanner scanner = new Scanner(System.in);

        System.out.println("계산 수식 : ");

 

        String susik = scanner.nextLine(); //엔터 치기 전까지 입력 해야함

 

        String[] operand = susik.split("\\+|\\-"); // suplit -> + or -를 만나면 쪼개라, 연산자 앞의 숫자를 배열에 넣음

        Queue<Character> operator = new LinkedList<Character>(); //문자라서 Character형

 

        for (int i = 0; i < susik.length(); i++) {

            if(susik.charAt(i)=='+') { //susik의 문자열에서 +를 만나면 +를 operator(큐)에 넣어라

                operator.add('+');

                continue;

            }    

            else if(susik.charAt(i)=='-') {

                operator.add('-');

                continue;

            }else {

                continue;    //숫자가 들어오면 계속 진행 되도록

            }

        }

        

        int plusSum = 0;    int minusSum = 0;    int result = 0;

        plusSum = Integer.parseInt(operand[0]); //Integer.parseInt 함수로 문자열을 정수로 바꿈

                                                // 첫번째 피연산자는 바로 넣음

        

        for (int i = 1; i < operand.length; i++) { //첫번째는 고정 했으니 2번째 부터 시작 -> i 초기값 1로 시작

            try {

                char ch = operator.poll(); //큐에서 데이터(연산자)를 꺼내옴, 만약 큐가 비어있다면 NULL을 반환

                if(ch == '+') {

                    plusSum += Integer.parseInt(operand[i]);

                    continue;

                }else if(ch == '-') {

                    minusSum += Integer.parseInt(operand[i]);

                    continue;

                }

            } catch (NullPointerException e) {

                break;

            }

        }

        result = (plusSum - minusSum);

        System.out.println("결과 : "+result);

    }

}