add package calculator

calculator/Add.java

@@ -0,0 +1,8 @@
+package calculator;
+
+public class Add implements Compute {
+    @Override
+    public int computer(int n, int m) {
+        return n + m;
+    }
+}

calculator/Compute.java

@@ -0,0 +1,5 @@
+package calculator;
+
+public interface Compute {
+    int computer(int n, int m);
+}

calculator/Divide.java

@@ -0,0 +1,8 @@
+package calculator;
+
+public class Divide implements Compute {
+    @Override
+    public int computer(int n, int m) {
+        return n / m;
+    }
+}

calculator/Factory.java

@@ -0,0 +1,18 @@
+package calculator;
+
+public class Factory {
+    public static Compute getCompute(char op) {
+        switch (op) {
+            case '+':
+                return new Add();
+            case '-':
+                return new Subtract();
+            case '*':
+                return new Multiply();
+            case '/':
+                return new Divide();
+            default:
+                return null;
+        }
+    }
+}

calculator/Multiply.java

@@ -0,0 +1,8 @@
+package calculator;
+
+public class Multiply implements Compute {
+    @Override
+    public int computer(int n, int m) {
+        return n * m;
+    }
+}

calculator/Subtract.java

@@ -0,0 +1,8 @@
+package calculator;
+
+public class Subtract implements Compute {
+    @Override
+    public int computer(int n, int m) {
+        return n - m;
+    }
+}

calculator/Test.java

@@ -0,0 +1,17 @@
+package calculator;
+
+import java.util.Scanner;
+
+public class Test {
+    public static void main(String[] args) {
+        try (Scanner sc = new Scanner(System.in)) {
+            while (true) {
+                System.out.print(">>> ");
+                int a = sc.nextInt();
+                char op = sc.next().charAt(0);
+                int b = sc.nextInt();
+                System.out.println(Factory.getCompute(op).computer(a, b));
+            }
+        }
+    }
+}