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Java 组合模式

组合模式是结构型模式,因为它创建了一组对象的树结构。

组合模式将一组对象视为单个对象。

组合模式使用一个类来表示树结构。

在组合模式中,我们创建一个包含自己对象的类的组。

例子

以下代码使用Employee类来演示组合模式。

import java.util.ArrayList;
import java.util.List;

class Employee {
   private String name;
   private String title;
   private List<Employee> subordinates;

   public Employee(String name,String title) {
      this.name = name;
      this.title = title;
      subordinates = new ArrayList<Employee>();
   }

   public void add(Employee e) {
      subordinates.add(e);
   }

   public void remove(Employee e) {
      subordinates.remove(e);
   }

   public List<Employee> getSubordinates(){
     return subordinates;
   }

   public String toString(){
      return "Employee :[ Name : "+ name 
      +", dept : "+ title +subordinates +" ]";
   }   
}

public class Main {
   public static void main(String[] args) {
      Employee CEO = new Employee("John","CEO");

      Employee headSales = new Employee("Rob","Sales");

      Employee headMarketing = new Employee("Mike","Marketing");

      Employee programmer1 = new Employee("Lili","Programmer");
      Employee programmer2 = new Employee("Bob","Programmer");

      Employee tester1 = new Employee("Jack","Tester");
      Employee tester2 = new Employee("Tom","Tester");

      CEO.add(headSales);
      CEO.add(headMarketing);

      headSales.add(tester1);
      headSales.add(tester2);

      headMarketing.add(programmer1);
      headMarketing.add(programmer2);

      //print all employees of the organization
      System.out.println(CEO); 
      for (Employee headEmployee : CEO.getSubordinates()) {
         System.out.println(headEmployee);
         for (Employee employee : headEmployee.getSubordinates()) {
            System.out.println(employee);
         }
      }    
   }
}

上面的代码生成以下结果。


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