Behavior pattern -- Null Object Pattern

1 空对象模式

2 代码实现。 

import javax.sound.midi.Soundbank;

abstract class Customer{
    protected String name;
    abstract boolean isNull();
    abstract String getName();
}

class RealCustomer extends Customer{
    public RealCustomer(String name) {
        this.name = name;
    }
    @Override
    boolean isNull() {
        return false;
    }
    @Override
    String getName() {
        return name;
    }
}
class NullCustomer extends Customer{
    @Override
    boolean isNull() {
        return true;
    }
    @Override
    String getName() {
        return "no this Customer";
    }
}
class CustomerFactory{
    private static final String[] names = {"zhangSan", "liSi", "wangWu"};
    public static Customer getCustomer(String name){
        for (String local : names){
            if (local.equals(name)){
                return new RealCustomer(name);
            }
        }
        return new NullCustomer();
    }
}
public class Test{
    public static void main(String[] args){
        Customer zhangsan = CustomerFactory.getCustomer("zhangSan");
        Customer shenLiu = CustomerFactory.getCustomer("shenLiu");

        System.out.println(zhangsan.getName());
        System.out.println(shenLiu.getName());
    }
}


import javax.s