嗨，我是Kotlin世界的新手。我喜欢我目前所看到的，并开始考虑将我们在应用程序中使用的一些库从Java转换为Kotlin。
这些库充满了带有setter、getter和Builder类的pojo。现在我已经在谷歌上找到了在Kotlin中实现Builders的最佳方法，但没有成功。
第二次更新:问题是如何写一个建设者设计模式的一个简单的pojo与一些参数在Kotlin?下面的代码是我尝试编写java代码，然后使用eclipse-kotlin-plugin转换为Kotlin。
class Car private constructor(builder:Car.Builder) {
var model:String? = null
var year:Int = 0
init {
this.model = builder.model
this.year = builder.year
}
companion object Builder {
var model:String? = null
private set
var year:Int = 0
private set
fun model(model:String):Builder {
this.model = model
return this
}
fun year(year:Int):Builder {
this.year = year
return this
}
fun build():Car {
val car = Car(this)
return car
}
}
}
在kotlin中可以使用可选参数
例子:
fun myFunc(p1: String, p2: Int = -1, p3: Long = -1, p4: String = "default") {
System.out.printf("parameter %s %d %d %s\n", p1, p2, p3, p4)
}
然后
myFunc("a")
myFunc("a", 1)
myFunc("a", 1, 2)
myFunc("a", 1, 2, "b")
我刚刚发现了一个有趣的方法来创建kotlin构建器:
如您所见，moduleBuilder可以用于其他grafana构建。
代码如下:
class Grafana(
private val module: String,
private val scene: String,
private val action: String,
private val metric: String
) {
companion object {
fun build(module: String, scene: String, action: String, metric: String) =
Grafana(module, scene, action, metric)
val builder = ::build.curriedBuilder()
private fun <P1, P2, P3, P4, R> Function4<P1, P2, P3, P4, R>.curriedBuilder() =
fun(p1: P1) = fun(p2: P2) = fun(p3: P3) = fun(p4: P4) = this(p1, p2, p3, p4)
}
fun report() = Unit
}
val moduleBuilder = Grafana.builder("module")
val scene = moduleBuilder("scene")
val gfA = scene("action")("metric")
gfA.report()
val sceneB = moduleBuilder("sceneB")
val gfB = sceneB("action")("metric")
gfB.report()
val gfC = Grafana.builder("xx")("xxx")("xxxx")("xxxx")
gfC.report()
class Person(
val name:String,
val family:String,
val age:Int,
val nationalCode: String?,
val email: String?,
val phoneNumber: String?
) {
// Private constructor
private constructor(builder: Builder) : this (
builder.name,
builder.family,
builder.age,
builder.nationalCode,
builder.email,
builder.phoneNumber
)
// Builder class
// 1 Necessary parameters in Builder class : name , family
class Builder(val name :String,val family :String) {
// 2 Optional parameters in Builder class :
var age: Int = 0
private set
var nationalCode: String? = null
private set
var email: String? = null
private set
var phoneNumber: String? = null
private set
fun age(age: Int) = apply { this.age = age }
fun nationalCode(nationalCode: String) =
apply { this.nationalCode = nationalCode }
fun email(email: String) = apply { this.email = email }
fun phoneNumber(phoneNumber: String) =
apply { this.phoneNumber = phoneNumber }
// 3 Create
fun create() = Person(this)
}
}
存取资料:
val firstPerson = Person.Builder(
name = "Adnan",
family = "Abdollah Zaki")
.age(32)
.email("Adnan9011@gmail.com")
.phoneNumber("+989333030XXX")
.nationalCode("04400XXXXX")
.create()
val secondPerson = Person.Builder(
name = "Foroogh",
family = "Varmazyar")
.create()
一种方法是做以下事情:
class Car(
val model: String?,
val color: String?,
val type: String?) {
data class Builder(
var model: String? = null,
var color: String? = null,
var type: String? = null) {
fun model(model: String) = apply { this.model = model }
fun color(color: String) = apply { this.color = color }
fun type(type: String) = apply { this.type = type }
fun build() = Car(model, color, type)
}
}
使用示例:
val car = Car.Builder()
.model("Ford Focus")
.color("Black")
.type("Type")
.build()
