java 如何在java中使用反射将字段转换为特定类？
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How to cast field to specific class using reflection in java?
提问by ZakTaccardi
I am using reflection to put all my class's member variables that are of type Cardclass into an ArrayList<Card>instance. How do I finish this last part (see commented line below)?
我正在使用反射将类的所有类成员变量Card放入一个ArrayList<Card>实例中。我如何完成最后一部分（请参阅下面的注释行）？
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?
回答by Thilo
Fieldis just the description of the field, it is not the value contained in there.
Field只是字段的描述，而不是其中包含的值。
You need to first get the value, and then you can cast it:
您需要先获取该值，然后才能对其进行转换：
Card x = (Card) field.get(this);
Also, you probably want to allow subclasses as well, so you should do
此外，您可能还希望允许子类，因此您应该这样做
// if (field.getType() == Card.class) {
if (Card.class.isAssignableFrom(field.getType()) {
回答by Mauro Midolo
ArrayList<Card> cardList = new ArrayList<Card>();
Field[] fields = this.getClass().getDeclaredFields();
for (Field field : fields) {
if (field.getType() == Card.class) {
Card tmp = (Card) field.get(this);
cardList.add(tmp);
