Java 反射 - 传入一个 ArrayList 作为要调用的方法的参数

Question

想将 arraylist 类型的参数传递给我要调用的方法。

我遇到了一些语法错误，所以我想知道这有什么问题。

场景一：

// i have a class called AW
class AW{}

// i would like to pass it an ArrayList of AW to a method I am invoking
// But i can AW is not a variable
Method onLoaded = SomeClass.class.getMethod("someMethod",  ArrayList<AW>.class );
Method onLoaded = SomeClass.class.getMethod("someMethod",  new Class[]{ArrayList<AnswerWrapper>.class}  );

场景2（不一样，但相似）：

// I am passing it as a variable to GSON, same syntax error
ArrayList<AW> answers = gson.fromJson(json.toString(), ArrayList<AW>.class);

Answer 1

您的（主要）错误是AW在您的getMethod()参数中传递了不必要的泛型类型。我试图编写一个与您类似但有效的简单代码。希望它可以以某种方式回答您的（某些）问题：

import java.util.ArrayList;
import java.lang.reflect.Method;

public class ReflectionTest {

  public static void main(String[] args) {
    try {
      Method onLoaded = SomeClass.class.getMethod("someMethod",  ArrayList.class );
      Method onLoaded2 = SomeClass.class.getMethod("someMethod",  new Class[]{ArrayList.class}  );    

      SomeClass someClass = new SomeClass();
      ArrayList<AW> list = new ArrayList<AW>();
      list.add(new AW());
      list.add(new AW());
      onLoaded.invoke(someClass, list); // List size : 2

      list.add(new AW());
      onLoaded2.invoke(someClass, list); // List size : 3

    } catch (Exception ex) {
      ex.printStackTrace();
    }
  }

}

class AW{}

class SomeClass{

  public void someMethod(ArrayList<AW> list) {
    int size = (list != null) ? list.size() : 0;  
    System.out.println("List size : " + size);
  }

}