确定成员类是嵌套还是内部？

Question

Suppose I have a class that contains come member classes, some of them nested (static) and some inner (non-static):

class Foo {
    static class A {}
    class B {}
    static class C {}
}

I would like to get all the nested member classes of Foo , ie A and C , but not B . Is this even possible? I know how to list all the member classes (using Foo.class.getDesclaredClasses() ), i see methods such as isLocalClass() , isMemberClass() or isAnonymousClass() on java.lang.Class , but I don't see anything like isNested() or isInner() .

Answer 1

You can use Modifier#isStatic(int mod) ( Return true if the integer argument includes the static modifier, false otherwise. ) to know if the inner-class is static or not.

Like this :

public class Demo {
public static void main(String[] args) {
    Class foo = Foo.class;
    Class[] declaredClasses = foo.getDeclaredClasses();
    for (Class class1 : declaredClasses) {
        System.out.println(Modifier.isStatic(class1.getModifiers()));
    }
}
}

class Foo {
    static class A {}
    class B {}
    static class C {}
}

Output :

true
false
true

Note : Class#getModifiers() -

Returns the Java language modifiers for this class or interface, encoded in an integer. The modifiers consist of the Java Virtual Machine's constants for public, protected, private, final, static, abstract and interface; they should be decoded using the methods of class Modifier.