문자열 계산기

src/stringCalculator/FormulaSplitter.java

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+package stringCalculator;
+
+public class FormulaSplitter {
+
+    public String[] split(String formula) {
+        return formula.split(" ");
+    }
+}

src/stringCalculator/InputProcessor.java

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+package stringCalculator;
+
+import java.util.Scanner;
+
+public class InputProcessor {
+    private final Scanner scanner = new Scanner(System.in);
+
+    public String input() {
+        System.out.print("계산식을 입력하세요(예:2 + 3 * 4 / 5): ");
+        return scanner.nextLine();
+    }
+}

src/stringCalculator/Operator.java

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+package stringCalculator;
+
+public enum Operator {
+    PLUS("+") {
+        @Override
+        int operation(int a, int b) {
+            return a + b;
+        }
+    },
+    MINUS("-"){
+        @Override
+        int operation(int a, int b) {
+            return a - b;
+        }
+    },
+    MULTIPLY("*"){
+        @Override
+        int operation(int a, int b) {
+            return a * b;
+        }
+    },
+    DIVIDE("/"){
+        @Override
+        int operation(int a, int b) {
+            if (b == 0) {
+                throw new IllegalArgumentException("0으로 나눌 수 없습니다.");
+            }
+            return a / b;
+        }
+    };
+
+    private final String message;
+
+    Operator(String message) {
+        this.message = message;
+    }
+
+    abstract int operation(int a, int b);
+
+    public static Operator conversion(String message) { //입력받은 연산자로 enum 찾기
+        for (Operator op : Operator.values()) {
+            if (op.message.equals(message)) {
+                return op;
+            }
+        }
+        throw new IllegalArgumentException("지원하지 않는 연산자: " + message);
+    }
+}

src/stringCalculator/OutputProcessor.java

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+package stringCalculator;
+
+public class OutputProcessor {
+
+    public void output(int result) {
+        System.out.println("결과: " + result);
+    }
+}

src/stringCalculator/StringCalculator.java

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+package stringCalculator;
+
+
+
+public class StringCalculator {
+
+    public int calculate(String[] values) {
+        try {
+
+        int result;
+        int number = Integer.parseInt(values[0]);
+
+            for (int i = 1; i < values.length; i += 2) {
+                Operator operator = Operator.conversion(values[i]);
+                int nextNumber = Integer.parseInt(values[i + 1]);
+
+                number = operator.operation(number, nextNumber);
+            }
+            result = number;
+            return result;
+        } catch (NumberFormatException e) {
+            throw new IllegalArgumentException("숫자가 아닌 값이 포함되어 있습니다." , e);
+        } catch (ArrayIndexOutOfBoundsException e) {
+            throw new IllegalArgumentException("잘못된 계산식입니다. 연산자와 숫자를 올바르게 입력하시오." , e);
+        }
+    }
+}
+
+

src/stringCalculator/StringCalculatorMain.java

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+package stringCalculator;
+
+public class StringCalculatorMain {
+    public static void main(String[] args) {
+        StringCalculator stringCalculator = new StringCalculator();
+        InputProcessor inputProcessor = new InputProcessor();
+        OutputProcessor outputProcessor = new OutputProcessor();
+        FormulaSplitter formulaSplitter = new FormulaSplitter();
+
+        String value = inputProcessor.input();
+        String[] values = formulaSplitter.split(value);
+
+        int result = stringCalculator.calculate(values);
+        outputProcessor.output(result);
+    }
+}