In Java, is it possible to have Interface in Inner class?

Your title and question are inconsistent!
Is it interfaces in inner classes, inner classes in interfaces?

Interfaces in inner classes:

Yes, sometimes.
Because interfaces are by definition static, they can only be declared in a static inner class.

class Testing {
    static class Inner {
        interface InnerInterface {

is legal, but

class Testing {
    class Inner {
        interface InnerInterface {

is not.

Inner classes in interfaces:


interface I {
    class C{}

is legal.

ps: You could have got a quicker answer by trying that code yourself!

Yes, an Interface can have an Inner Class.
Following will help you, once you apply this in Java:

public interface abc
static int i=0;
void dd();
class a1 {
a1() {
int j;
public static void main(String a1[]) } }

To clear your confusion read about Inner Class

commented: Unreadable pile of invalid code. Useless. -3

Wow. When did we last see such a useless pile of nonsense. Almost every line contains an error. There's no way you could turn that into valid Java code.
And the link is to a useless tutorial that doesn't actually explain anything and doesn't even use normal Java coding standards.

If you are looking for a tutorial there's only one that is up-to-date, comprehensive, and correct, and that's Oracle's own...

commented: Maybe they are trying to make the Kessel run in less than 12 parsecs? +0