chaining ..체이닝 체인 구성... 구현형태 확장 형태 extends 포함

간단하다... 론 패턴.. loan pattern

package com.javaTest.lamda;

public class Person {


    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Person() {
    }

    String name;
    int age;

    public String getName() {
        return name;
    }

    public Person setName(String name) {
        this.name = name;
        return this;
    }

    public int getAge() {
        return age;
    }

    public Person setAge(int age) {
        this.age = age;
        return this;
    }

    @Override
    public String toString() {
        return "{name:"+this.name+",age:"+this.age+"}";
        //return super.toString();
    }

    public int ageDifference(Person other) {
        return age - other.age;
    }
}

자 흔한 vo 인데... 잘보면 return this; 즉 자신을 리턴하고 있다. 객체를...

public void chaining001() {
    Person person = new Person().setAge(10).setName("dr.who");

    System.out.println(person.toString());
}

자.. 이렇게 체이닝이 만들어진다. 간단하지?

근데 문제는... 만약 vo 가 확장 vo 라면?

확장시 타입을 확실히 선언해주면된다. ( 참고 https://stackoverflow.com/questions/1069528/method-chaining-inheritance-don-t-play-well-together )

// XXX base 가 되는 클래스는 타입을 선언해줘야함
class Pet<T extends Pet>
{
    private String name;
    private String color;

    public T setName(String name) {
        this.name = name;
        return (T) this;
    }

    public String getName() {
        return name;
    }

    public String getColor() {
        return color;
    }

    public T setColor(String color) {
        this.color = color;
        return (T) this;
    }
}

// XXX 확장한 클래스는 베이스 클래스에게 타입을 알려줘야함(여기서는 Cat)
class Cat extends Pet<Cat>
{
    private String sand;
    private String hair;

    public String getSand() {
        return sand;
    }

    public Cat setSand(String sand) {
        this.sand = sand;
        return this;
    }

    public String getHair() {
        return hair;
    }

    public Cat setHair(String hair) {
        this.hair = hair;
        return this;
    }
}

class Dog extends Pet<Dog>
{
    private String takeawalk;
    private String vitality;

    public String getTakeawalk() {
        return takeawalk;
    }

    public Dog setTakeawalk(String takeawalk) {
        this.takeawalk = takeawalk;
        return this;
    }

    public String getVitality() {
        return vitality;
    }

    public Dog setVitality(String vitality) {
        this.vitality = vitality;
        return this;
    }
}

@Test
public void chaining001() {
    Person person = new Person().setAge(10).setName("dr.who");

    System.out.println(person.toString());


    Cat cat = new Cat();
    cat.setName("shasha").setHair("short").setSand("normal").setColor("mix");

    Dog dog = new Dog();
    dog.setName("jindol").setVitality("very good").setColor("brown").setTakeawalk("daily");
}