[4기][이윤수] 문자열 계산기 과제

README.md

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+## 다이어그램
+<img width="838" alt="image" src="https://user-images.githubusercontent.com/77106988/215942113-a09c8587-8ca6-431b-9552-4c974f11ceec.png">
+
+## 구현 기능
+- [X] 입력을 받았을 경우 사칙연산(+, -, *, /)이 가능해야 한다.
+
+- [ ] 숫자에 소수를 적용해본다.
+
+- [ ] 사칙연산 우선순위를 적용한다.
+
 ## 깃허브
 
 **[java-calculator](https://github.com/programmers-lecture/java-calculator)**

src/main/java/stringCalculator/Calculator.java

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+package stringCalculator;
+
+import java.util.regex.Pattern;
+
+public class Calculator {
+
+    private static final Pattern regExp = Pattern.compile("^[0-9]*$"); //operand, operator 구분 용도
+
+    public int calculate(String[] inputExp){
+
+        int result = 0;
+        // 맨처음 숫자 더해짐
+        Operator currentOperator = Operator.PLUS;
+
+        for(String input : inputExp){
+            if(regExp.matcher(input).find()){
+                result = currentOperator.operate(result, Integer.parseInt(input));
+                continue;
+            }
+            // 연산자 매칭
+            for(Operator operator : Operator.values()){
+                if(operator.getSymbol().equals(input)){
+                    currentOperator = operator;
+                }
+            }
+        }
+
+        return result;
+    }
+}

src/main/java/stringCalculator/Main.java

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+package stringCalculator;
+
+import java.util.Scanner;
+
+public class Main {
+
+    public static void main(String[] args) {
+        Calculator calculator = new Calculator();
+        String[] input = receiveInput();
+        int result = calculator.calculate(input);
+        System.out.println("결과 : " + result);
+    }
+
+    public static String[] receiveInput() {
+        Scanner sc = new Scanner(System.in);
+        String input = sc.nextLine().replaceAll("\\s+", " ");
+        return input.split(" ");
+    }
+}

src/main/java/stringCalculator/Operator.java

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+package stringCalculator;
+
+import java.util.function.BiFunction;
+
+public enum Operator {
+    PLUS("+", (first, second) -> first + second),
+    MINUS("-", (first, second) -> first - second),
+    MULTIPLY("*", (first, second) -> first * second),
+    DIVIDE("/", (first, second) -> first / second);
+
+    private String symbol;
+    private BiFunction<Integer, Integer, Integer> operation;
+
+    Operator(String symbol, BiFunction<Integer, Integer, Integer> operation) {
+        this.symbol = symbol;
+        this.operation = operation;
+    }
+
+    public String getSymbol(){ return symbol; }
+
+    public int operate(int first, int second) {
+        return operation.apply(first, second);
+    }
+
+
+}