【Kotlin设计模式】Java的建造者模式在Kotlin的实现

• 建造者模式

Java

public class Pen {
	private Builder builder;
	
	public Pen(Builder builder) {
		this.builder = builder;
	}

	public void write(){
		System.out.println("color: "+builder.color+", width: "+builder.width+", round: "+builder.round);
	}

	public static class Builder {
		private String color = "white";
		private Float width = 1.0f;
		private Boolean round = false;

		public Builder color(String color) {
			this.color = color:
			return this;
		}
		
		public Builder width(Float width) {
			this.width = width ;
			return this;
		}
		
		public Builder round(Boolean round) {
			this.round = round ;
			return this;
		}

		public Pen build(){
			return new Pen();
		}
	}
}

使用

fun main() {
	val pen = Pen.Builder().color("yellow").width(3f).round(true).build()
	pen.write( )
}

kotlin

class Pen {
	var color: String = "white"
	var width: Float = 1.0f
	var round: Boolean = false
	
	fun write(){ 
		printIn("color:${color}, width:${width}, round:${round}")
	}
}

使用

fun main(){
	val pen = Pen()
	//通过with来实现
	with(pen, {
		color ="red"
		width = 2f
		round = t rue
	})
	pen.write()

	pen.apply {
		color = "gray" 
		width = 6f
		round = false
		write()
	}
}