Java问题中的工厂方法模式示例

Question

我正在尝试用Java创建一个非常简单的Factory Method设计模式示例.我真的不懂Java,我不熟悉编程,但我需要提出一个在java中实现的基本FactoryMethod示例.以下是我提出的建议.我确定有很多错误,我显然缺少一些构造函数,而且我对抽象类和接口感到困惑.你能指出我的错误并纠正我的代码以及解释吗？提前感谢您的时间和帮助.

public abstract class Person 
{   
    public void createPerson(){ }
}

public class Male extends Person 
{   
    @Override
    public void createPerson() 
    {
        System.out.print("a man has been created");
    }
}

public class Female extends Person 
{   
    @Override
    public void createPerson() 
    {
        System.out.print("a woman has been created");
    }
}

public class PersonFactory
{
     public static Person makePerson(String x) // I have no Person constructor in
     {                                         // the actual abstract person class so 
         if(x=="male")                         // is this valid here?
         { 
             Male man=new Male();
             return man;
          }
          else
         {
             Female woman=new Female();
             return woman;
         }
     }
}


public class Test 
{
    public static void main(String[] args)
    {
       Person y= new Person(makePerson("male"));   // definitely doing smth wrong here
       Person z= new Person(makePerson("female")); // yup, here as well
    }
}

Answer 1

简而言之,您的版本中有几个问题已在下面更正:

1. createPerson 方法没用.
2. 调用工厂方法的方式是错误的.
3. 您使用==而不是.equals在工厂方法中.

我已经增强了你的Person类,以添加一个由Male和Female类共享的成员字段,以演示如何使用共享的常见抽象构造函数.

public abstract class Person {   
    protected final String name;
    public Person(String name) { 
        this.name = name;
    }
}

public class Male extends Person {
    public Male(String name) { 
        super(name);
    }
}

public class Female extends Person {
    public Female(String name) { 
        super(name);
    }
}

public class PersonFactory
{
     public static Person makePerson(String gender, String name) 
     {
         if(gender.equals("male"))                       
         { 
             Male man=new Male(name);
             return man;
         }
         else
         {
             Female woman=new Female(name);
             return woman;
         }
     }
}

public class Test 
{
    public static void main(String[] args)
    {
       Person y= PersonFactory.makePerson("male", "bob"));
       Person z= new PersonFactory.makePerson("female", "janet"));
    }
}