如何在Java中使用反射将字段强制转换为特定类? [英] How to cast field to specific class using reflection in java?

问题描述

我正在使用反射将所有类型为 Card 类的类的所有成员变量放入 ArrayList< Card> 实例中.如何完成最后一部分(请参见下面的注释行)?

I am using reflection to put all my class's member variables that are of type Card class into an ArrayList<Card> instance. How do I finish this last part (see commented line below)?

ArrayList<Card> cardList = new ArrayList<Card>();
Field[] fields = this.getClass().getDeclaredFields();

for (Field field : fields) {
   if (field.getType() == Card.class) {
      //how do I convert 'field' to a 'Card' object and add it to the 'cardList' here?

推荐答案

Field 只是对该字段的描述，而不是其中包含的值.

Field is just the description of the field, it is not the value contained in there.

您需要先获取该值，然后才能对其进行转换:

You need to first get the value, and then you can cast it:

Card x =  (Card) field.get(this);

此外，您可能还希望允许子类，所以您应该这样做

Also, you probably want to allow subclasses as well, so you should do

  //  if (field.getType() == Card.class) {

  if (Card.class.isAssignableFrom(field.getType()) {

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