如何在运行时测试一个 java 类是否扩展了另一个 java 类？
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How to test if one java class extends another at runtime?
提问by Armand
How to I test if ais a subclass of b?
如何测试是否a是 的子类b？
Class<?> a = A.class;
Class<?> b = B.class;
采纳答案by meriton
Are you looking for:
您是否正在寻找：
Super.class.isAssignableFrom(Sub.class)
回答by Rob Hruska
If you want to know whether or not a Classextends another, use Class#isAssignableFrom(Class). For your example, it would be:
如果您想知道 a 是否Class扩展了另一个，请使用Class#isAssignableFrom(Class)。对于您的示例，它将是：
if(B.class.isAssignableFrom(A.class)) { ... }
If you're interested in whether or not an instance is of a particular type, use instanceof:
如果您对实例是否属于特定类型感兴趣，请使用instanceof：
A obj = new A();
if(obj instanceof B) { ... }
Note that these will return trueif the class/instance is a member of the type hierarchy and are not restrictive to direct superclass/subclass relationships. For example:
请注意，true如果类/实例是类型层次结构的成员并且不受直接超类/子类关系的限制，则这些将返回。例如：
// if A.class extends B.class, and B.class extends C.class
C.class.isAssignableFrom(A.class); // evaluates to true
// ...and...
new A() instanceof C; // evaluates to true
If you want to check for direct superclass/subclass relationships, Tim has provided an answeras well.
如果您想检查直接的超类/子类关系，Tim 也提供了答案。
回答by Tim Stone
You want to know if bis assignable froma:
b.isAssignableFrom(a);
Additionally, if you want to know that ais a direct subclass of b:
此外，如果您想知道它a是 的直接子类b：
a.getSuperclass().equals(b);
