如何使用反射實例化內部類？

Question

我想獲得一個嵌套類的構造函數，以便可以實例化它。 我希望這是一個內部類，以便我可以從其外部類訪問變量。

下面的代碼拋出NoSuchMethodException，並添加了inner前綴：

package com.example

import android.util.Log

class ClassA {

    var iWantToUseThisFromTheInnerClass = "someValue"

    fun runThisToStart() {
        val classB = ClassB(InnerClassA::class.java)
        classB.doSomething()

    }

    inner class InnerClassA(text: String) {
        init {
            Log.d("InnerClassA", "Constructor invoked " + text)
        }
    }

}

---

package com.example

import java.lang.reflect.InvocationTargetException

class ClassB<T>(private var mModelClass: Class<T>) {

    val someText = "whatever"

    fun doSomething():T {
        try {
            val constructor = mModelClass.getConstructor(String::class.java)
            return constructor.newInstance(someText)
        } catch (e: NoSuchMethodException) {   // Throws this exception
            throw RuntimeException(e)
        } catch (e: InvocationTargetException) {
            throw RuntimeException(e)
        } catch (e: InstantiationException) {
            throw RuntimeException(e)
        } catch (e: IllegalAccessException) {
            throw RuntimeException(e)
        }
    }

}

謝謝

Answer 1

您還需要在構造函數中包括封閉類（ClassA）實例，因為如果沒有它，InnerClassA將不存在：

class ClassA {

    var iWantToUseThisFromTheInnerClass = "someValue"

    fun runThisToStart() {
        val classB = ClassB(InnerClassA::class.java)
        classB.doSomething(this)

    }

    inner class InnerClassA(text: String) {
        init {
         //   Log.d("InnerClassA", "Constructor invoked " + text)
        }
    }

}

class ClassB<T>(private var mModelClass: Class<T>) {

    val someText = "whatever"

    fun doSomething(enclosingObj : Any):T {
            val constructor = mModelClass.getConstructor(enclosingObj::class.java, String::class.java)
            return constructor.newInstance(enclosingObj, someText)
    }

}