如何使用反射实例化具有泛型类的java.util.ArrayList [英] How To Instantiate a java.util.ArrayList with Generic Class Using Reflection

问题描述

如何使用反射实例化具有泛型类的java.util.ArrayList？我正在编写一个在目标对象上设置java.util.List的方法。目标对象和通用类型的列表在运行时知道：

How To Instantiate a java.util.ArrayList with Generic Class Using Reflection? I am writing a method that sets java.util.List on target object. A target object and a generic type of list is knowing in runtime:

public static void initializeList(Object targetObject, PropertyDescriptor prop, String gtype) {
    try {
        Class clazz = Class.forName("java.util.ArrayList<"+gtype+">");
        Object newInstance = clazz.newInstance();
        prop.getWriteMethod().invoke(targetObject, newInstance);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

推荐答案

object在执行时不知道它的泛型类型。只需创建一个原始类型的新实例（ java.util.ArrayList ）。目标对象不会知道差异（因为不是任何区别）。

An object doesn't know about its generic type at execution time. Just create a new instance of the raw type (java.util.ArrayList). The target object won't know the difference (because there isn't any difference).

基本上Java泛型是一个编译时的技巧，在编译的类中使用元数据，但只是在执行时进行转换。有关详细信息，请参阅 Java泛型常见问题解答。

Basically Java generics is a compile-time trick, with metadata in the compiled classes but just casting at execution time. See the Java generics FAQ for more information.

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