Builder Pattern, 빌더 패턴, JAVA

1. Class 초기화에 사용하는 일반적인 방법

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1-1. Class 예시:

package init.pattern.example;

public class Person {
	private String name = "CHAE";
	private String id = "4600";
	private int age = 20;
	private int weight = 100;
	private int height = 180;
	private String phone = "02-1234-5678";

	public Person()
	{}
	
	public Person(String name,  String id, int age, int weight, int height, String phone) {
		this.name = name;
		this.id = id;
		this.age = age;
		this.weight = weight;
		this.height = height;
		this.phone = phone;
	}
	
	public void print()
	{
		System.out.println("NAME: "+ name + " ID: "+ id);
		System.out.println("AGE: " + age + " WEIGHT: "+ weight + " HEIGHT: " + height + " PHONE: " + phone);
	}
	
	public void name(String name) {
		this.name = name;
	}
	
	public void id(String id) {
		this.id = id;
	}
	
	public void age(int age) {
		this.age = age;
	}
	
	public void weight(int weight) {
		this.weight = weight;
	}
	
	public void height(int height) {
		this.height = height;
	}
	
	public void phone(String phone) {
		this.phone = phone;
	}
	

}

   

1-2. 사용 예시:

package init.pattern.example;

public class MainCommon {

	public static void main(String[] args) {
		
		Person p1 = new Person("CHAE", "1500", 50, 60, 150, "02-1111-2222");
		p1.print();
		
		Person p2 = new Person();
		p2.name("KIM");
		p2.id("3200");
		p2.age(40);
		p2.print();
	}

}

 

 

 

1-3. 출력 예시:

NAME: CHAE ID: 1500
AGE: 50 WEIGHT: 60 HEIGHT: 150 PHONE: 02-1111-2222
NAME: KIM ID: 3200
AGE: 40 WEIGHT: 100 HEIGHT: 180 PHONE: 02-1234-5678

 

1-4. 불편한 점:

- 초기화 변수가 많아질 수록 코드가 길어짐.

- 필수 초기화 변수와 선택적 초기화 변수 구분 가독성이 떨어짐.

 

 

 

 

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2. Class 초기화 변수가 많은 경우 유용한 Builder 패턴

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2-1. Class 예시:

package builder.pattern.example;

public class Person {
	private final String name;
	private final String id;
	private final int age;
	private final int weight;
	private final int height;
	private final String phone;
	
	private Person(Builder builder) {
		name = builder.name;
		id = builder.id;
		age = builder.age;
		weight = builder.weight;
		height = builder.height;
		phone = builder.phone;
		
	}
	
	public void print()
	{
		System.out.println("NAME: "+ name + " ID: "+ id);
		System.out.println("AGE: " + age + " WEIGHT: "+ weight + " HEIGHT: " + height + " PHONE: " + phone);
	}
	
	public static class Builder{
		//essential param.
		private final String name;
		private final String id;
		
		//optional param.
		private int age = 50;
		private int weight = 100;
		private int height = 175;
		private String phone = "02-1234-5678";
		
		
		
		public Builder(String name, String id){
			this.name = name;
			this.id = id;
		}
		
		public Builder age(int val){
			age = val;
			return this;
		}
		
		public Builder weight(int val){
			weight = val;
			return this;
		}
		
		public Builder height(int val){
			height = val;
			return this;
		}
		
		public Builder phone(String val){
			phone = val;
			return this;
		}
		
		public Person build(){
			return new Person(this);
		}
		
	}
	


}

 

2-2. 사용 예시:

package builder.pattern.example;

public class MainBuilder {

	public static void main(String[] args) {

		Person p1 = new Person.Builder("CHAE", "8900").age(30).weight(80).height(190).phone("02-1111-2222").build();
		p1.print();
		
		Person p2 = new Person.Builder("KIM", "1200").age(28).build();
		p2.print();
		
		

	}

}

 

2-3. 출력 예시:

NAME: CHAE ID: 8900
AGE: 30 WEIGHT: 80 HEIGHT: 190 PHONE: 02-1111-2222
NAME: KIM ID: 1200
AGE: 28 WEIGHT: 100 HEIGHT: 175 PHONE: 02-1234-5678

 

2-4. 개인 의견:

- Class 초기화 변수가 많거나 늘어날 것 같은 경우, 유용한 패턴이 될 것 같음.

- Class 초기화 변수가 적은 경우, 불필요할 것 같음(오히려 구현하는 시간이 아까울 것 같음) 

 

 

# CODE: https://gitlab.com/YuJungChae/design_pattern/tree/builder_pattern