Replace Subclass with Fields

你的各个子类的唯一差别只在 "返回常量数据" 的函数身上.

修改这些函数,使他们返回超类中的某个字段,然后销毁子类;

如果子类没有其他的行为函数,就应该去掉这个继承体系;太简单了,没必要使用继承;

public  class Person {
//    abstract boolean isMale();

//    abstract char getCode();

    private final boolean isMale;
    private final char getCode;

    protected Person(boolean male, char code) {
        isMale = male;
        getCode = code;
    }

    public boolean isMale() {
        return isMale;
    }

    public char getCode() {
        return getCode;
    }

    static Person createMale() {
        return new Person(true, 'M');
    }

    static Person createFemale() {
        return new Person(false, 'F');
    }

    public static void main(String[] args) {
        Person male = Person.createMale();
        Person female = Person.createFemale();


        char maleCode = male.getCode();
        System.out.println(maleCode);
        boolean maleMale = male.isMale();
        System.out.println(maleMale);


        char femaleCode = female.getCode();
        System.out.println(femaleCode);
        boolean femaleMale = female.isMale();
        System.out.println(femaleMale);
    }
}

/*class Male extends Person {
    Male() {
        super(true, 'M');
    }

//    @Override
//    boolean isMale() {
//        return true;
//    }

//    @Override
//    char getCode() {
//        return 'M';
//    }
}*/

/*class Female extends Person {

    Female() {
        super(false, 'F');
    }

//    @Override
//    boolean isMale() {
//        return false;
//    }

//    @Override
//    char getCode() {
//        return 'F';
//    }
}*/