feat: 입출력 인터페이스 구현

Author: wonu606

calculator/src/main/java/com/wonu606/Main.java

@@ -1,8 +1,29 @@
 package com.wonu606;
 
+import com.wonu606.app.App;
+import com.wonu606.calculator.CalculatorApp;
+import com.wonu606.io.Input;
+import com.wonu606.io.Print;
+import java.io.IOException;
+
 public class Main {
 
     public static void main(String[] args) {
-        System.out.println("Hello world!");
+        Input input;
+        Print printer;
+
+        CalculatorApp app = new CalculatorApp();
+        try {
+            runApp(app, input, printer);
+        } catch (Exception exception) {
+            printer.print(exception.getMessage());
+        } finally {
+            input.tearDown();
+            printer.tearDown();
+        }
+    }
+
+    private static void runApp(App app, Input input, Print printer) throws IOException {
+        app.execute(input, printer);
     }
-}
+}

calculator/src/main/java/com/wonu606/app/App.java

@@ -0,0 +1,10 @@
+package com.wonu606.app;
+
+import com.wonu606.io.Input;
+import com.wonu606.io.Print;
+import java.io.IOException;
+
+public interface App {
+
+    void execute(Input input, Print printer) throws IOException;
+}

calculator/src/main/java/com/wonu606/calculator/CalculatorApp.java

@@ -0,0 +1,21 @@
+package com.wonu606.calculator;
+
+import com.wonu606.app.App;
+import com.wonu606.io.Input;
+import com.wonu606.io.Print;
+import java.io.IOException;
+
+public class CalculatorApp implements App {
+
+    Input input;
+    Print printer;
+
+    public void execute(Input input, Print printer) throws IOException {
+        this.input = input;
+        this.printer = printer;
+
+        while (true) {
+            String selection = input.getInput();
+        }
+    }
+}

calculator/src/main/java/com/wonu606/io/Input.java

@@ -0,0 +1,10 @@
+package com.wonu606.io;
+
+import java.io.IOException;
+
+public interface Input {
+
+    String getInput() throws IOException;
+
+    void tearDown();
+}

calculator/src/main/java/com/wonu606/io/Print.java

@@ -0,0 +1,10 @@
+package com.wonu606.io;
+
+public interface Print {
+
+    void print(String message);
+
+    void print(int number);
+
+    void tearDown();
+}