我使用以下初始化:
val entityClass = javaClass<Class<T>>()
var entity = entityClass.newInstance().newInstance()
但它是错的,并导致IllegalAccessException上java.lang.Class.newInstance(Class.java:1208)
为什么这不编译？我在3行中得到编译错误
不能使用T作为reified类型参数.请改用类
class Matrix2d<T>(val rows: Int, val cols: Int, init: (Int, Int) -> T) {
var data = Array(rows * cols, { i ->
val r = Math.floor(i.toDouble() / cols).toInt()
init(r, i - r * cols)
})
operator fun get(row: Int, col: Int): T = data[row * cols + col]
operator fun set(row: Int, col: Int, v: T) = {
data[row * cols + col] = v
}
}
解
我添加了一个工厂函数,它看起来像第二个构造函数,但是在内联函数中实现
class Matrix2d<T>(val rows: Int, val cols: Int, private val …我想从泛型类型获取类属性T.我决定延伸到Any但是我收到了一个错误.
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin/-any/index.html#extension-properties
我有以下代码:
class FirebaseDBRepo<T : Any>(val child:String) {
private var callback: FirebaseDatabaseRepositoryCallback<T>? = null
private val ref: DatabaseReference
private val listener = object : ValueEventListener {
override fun onDataChange(dataSnapshot: DataSnapshot) {
//T::class.java is showing the error cannot use t as reified type parameter use class instead
val gameDS = dataSnapshot.getValue(T::class.java)
callback!!.onSuccess(gameDS!!)
}
override fun onCancelled(databaseError: DatabaseError) {
}
}
init {
ref = FirebaseDatabase.getInstance().reference.child(child)
}
fun addListener(callback: FirebaseDatabaseRepositoryCallback<T>) {
this.callback = callback
ref.addValueEventListener(listener)
}
fun …