refactoring : mutable data - split variable

refactoring/src/main/java/com/example/refactoring/_06_mutable_data/_18_split_variable/Haggis.java

@@ -0,0 +1,33 @@
+package com.example.refactoring._06_mutable_data._18_split_variable;
+
+public class Haggis {
+
+    private double primaryForce;
+    private double secondaryForce;
+    private double mass;
+    private int delay;
+
+    public Haggis(double primaryForce, double secondaryForce, double mass, int delay) {
+        this.primaryForce = primaryForce;
+        this.secondaryForce = secondaryForce;
+        this.mass = mass;
+        this.delay = delay;
+    }
+
+    public double distanceTravelled(int time) {
+        double result;
+        // 가독성을 위해 변수의 이름을 역할에 맞도록 변경 변수의 값이 변경되지 않도록 final 키워드 사용
+        final double primaryAcceleration = primaryForce / mass;
+        int primaryTime = Math.min(time, delay);
+        result = 0.5 * primaryAcceleration * primaryTime * primaryTime;
+
+        int secondaryTime = time - delay;
+        if (secondaryTime > 0) {
+            final double primaryVelocity = primaryAcceleration * delay;
+            final double secondaryAcceleration = (primaryForce + secondaryForce) / mass;
+            result += primaryVelocity * secondaryTime + 0.5 * secondaryAcceleration * secondaryTime + secondaryTime;
+        }
+
+        return result;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_06_mutable_data/_18_split_variable/Order.java

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+package com.example.refactoring._06_mutable_data._18_split_variable;
+
+public class Order {
+
+    public double discount(double inputValue, int quantity) {
+        double result = inputValue;
+
+        if (inputValue > 50) result -= 2;
+        if (quantity > 100) result -= 1;
+
+        return result;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_06_mutable_data/_18_split_variable/Rectangle.java

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+package com.example.refactoring._06_mutable_data._18_split_variable;
+
+public class Rectangle {
+
+    private double perimeter;
+    private double area;
+
+    public void updateGeometry(double height, double width) {
+        // 가독성을 위해 변수의 이름을 역할에 맞도록 변경 변수의 값이 변경되지 않도록 final 키워드 사용
+        final double perimeter = 2 * (height + width);
+        System.out.println("Perimeter: " + perimeter);
+        this.perimeter = perimeter;
+
+        final double area = height * width;
+        System.out.println("Area: " + area);
+        this.area = area;
+    }
+
+    public double getPerimeter() {
+        return perimeter;
+    }
+
+    public double getArea() {
+        return area;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_06_mutable_data/_18_split_variable/before/Haggis.java

@@ -0,0 +1,32 @@
+package com.example.refactoring._06_mutable_data._18_split_variable.before;
+
+public class Haggis {
+
+    private double primaryForce;
+    private double secondaryForce;
+    private double mass;
+    private int delay;
+
+    public Haggis(double primaryForce, double secondaryForce, double mass, int delay) {
+        this.primaryForce = primaryForce;
+        this.secondaryForce = secondaryForce;
+        this.mass = mass;
+        this.delay = delay;
+    }
+
+    public double distanceTravelled(int time) {
+        double result;
+        double acc = primaryForce / mass;
+        int primaryTime = Math.min(time, delay);
+        result = 0.5 * acc * primaryTime * primaryTime;
+
+        int secondaryTime = time - delay;
+        if (secondaryTime > 0) {
+            double primaryVelocity = acc * delay;
+            acc = (primaryForce + secondaryForce) / mass;
+            result += primaryVelocity * secondaryTime + 0.5 * acc * secondaryTime + secondaryTime;
+        }
+
+        return result;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_06_mutable_data/_18_split_variable/before/Order.java

@@ -0,0 +1,10 @@
+package com.example.refactoring._06_mutable_data._18_split_variable.before;
+
+public class Order {
+
+    public double discount(double inputValue, int quantity) {
+        if (inputValue > 50) inputValue = inputValue - 2;
+        if (quantity > 100) inputValue = inputValue - 1;
+        return inputValue;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_06_mutable_data/_18_split_variable/before/Rectangle.java

@@ -0,0 +1,25 @@
+package com.example.refactoring._06_mutable_data._18_split_variable.before;
+
+public class Rectangle {
+
+    private double perimeter;
+    private double area;
+
+    public void updateGeometry(double height, double width) {
+        double temp = 2 * (height + width);
+        System.out.println("Perimeter: " + temp);
+        perimeter = temp;
+
+        temp = height * width;
+        System.out.println("Area: " + temp);
+        area = temp;
+    }
+
+    public double getPerimeter() {
+        return perimeter;
+    }
+
+    public double getArea() {
+        return area;
+    }
+}

refactoring/src/test/java/com/example/refactoring/_06_mutable_data/_18_split_variable/HaggisTest.java

@@ -0,0 +1,16 @@
+package com.example.refactoring._06_mutable_data._18_split_variable;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class HaggisTest {
+
+    @Test
+    void distance() {
+        Haggis haggis = new Haggis(10d, 20d, 10, 5);
+        assertEquals(50d, haggis.distanceTravelled(10));
+        assertEquals(125d, haggis.distanceTravelled(20));
+    }
+
+}

refactoring/src/test/java/com/example/refactoring/_06_mutable_data/_18_split_variable/OrderTest.java

@@ -0,0 +1,18 @@
+package com.example.refactoring._06_mutable_data._18_split_variable;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class OrderTest {
+
+    @Test
+    void discount() {
+        Order order = new Order();
+        assertEquals(50d, order.discount(50d, 100));
+        assertEquals(51d - 2, order.discount(51d, 100));
+        assertEquals(50d - 1, order.discount(50d, 101));
+        assertEquals(51d - 2 - 1, order.discount(51d, 101));
+    }
+
+}

refactoring/src/test/java/com/example/refactoring/_06_mutable_data/_18_split_variable/RectangleTest.java

@@ -0,0 +1,21 @@
+package com.example.refactoring._06_mutable_data._18_split_variable;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class RectangleTest {
+
+    @Test
+    void updateGeomerty() {
+        Rectangle rectangle = new Rectangle();
+        rectangle.updateGeometry(10, 5);
+        assertEquals(50d,rectangle.getArea());
+        assertEquals(30d, rectangle.getPerimeter());
+
+        rectangle.updateGeometry(5, 5);
+        assertEquals(25d,rectangle.getArea());
+        assertEquals(20d, rectangle.getPerimeter());
+    }
+
+}