refactoring : large class - extract superclass

refactoring/src/main/java/com/example/refactoring/_20_large_class/_41_extract_superclass/Department.java

@@ -0,0 +1,25 @@
+package com.example.refactoring._20_large_class._41_extract_superclass;
+
+import java.util.List;
+
+public class Department extends Party {
+
+    private List<Employee> staff;
+
+    public Department(String name) {
+        super(name);
+    }
+
+    @Override
+    public double monthlyCost() {
+        return this.staff.stream().mapToDouble(Employee::monthlyCost).sum();
+    }
+
+    public List<Employee> getStaff() {
+        return staff;
+    }
+
+    public int headCount() {
+        return this.staff.size();
+    }
+}

refactoring/src/main/java/com/example/refactoring/_20_large_class/_41_extract_superclass/Employee.java

@@ -0,0 +1,21 @@
+package com.example.refactoring._20_large_class._41_extract_superclass;
+
+public class Employee extends Party {
+
+    private Integer id;
+
+    private double monthlyCost;
+
+    public Employee(String name) {
+        super(name);
+    }
+
+    @Override
+    public double monthlyCost() {
+        return monthlyCost;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_20_large_class/_41_extract_superclass/Party.java

@@ -0,0 +1,19 @@
+package com.example.refactoring._20_large_class._41_extract_superclass;
+
+public abstract class Party {
+    protected String name;
+
+    public Party(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public double annualCost() {
+        return this.monthlyCost() * 12;
+    }
+
+    public abstract double monthlyCost();
+}

refactoring/src/main/java/com/example/refactoring/_20_large_class/_41_extract_superclass/_before/Department.java

@@ -0,0 +1,30 @@
+package com.example.refactoring._20_large_class._41_extract_superclass._before;
+
+import java.util.List;
+
+public class Department {
+
+    private String name;
+
+    private List<Employee> staff;
+
+    public String getName() {
+        return name;
+    }
+
+    public List<Employee> getStaff() {
+        return staff;
+    }
+
+    public double totalMonthlyCost() {
+        return this.staff.stream().mapToDouble(e -> e.getMonthlyCost()).sum();
+    }
+
+    public double totalAnnualCost() {
+        return this.totalMonthlyCost() * 12;
+    }
+
+    public int headCount() {
+        return this.staff.size();
+    }
+}

refactoring/src/main/java/com/example/refactoring/_20_large_class/_41_extract_superclass/_before/Employee.java

@@ -0,0 +1,26 @@
+package com.example.refactoring._20_large_class._41_extract_superclass._before;
+
+public class Employee {
+
+    private Integer id;
+
+    private String name;
+
+    private double monthlyCost;
+
+    public double annualCost() {
+        return this.monthlyCost * 12;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public double getMonthlyCost() {
+        return monthlyCost;
+    }
+}