【Kotlin设计模式】Java的建造者模式在Kotlin的实现

Kotlin设计模式.Java的建造者模式在Kotlin的实现

• ​​建造者模式​​

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()
  }
}