Java — Properties of a method-local inner class (what modifiers are allowed?)

Introduction / Context:
This question verifies which modifiers are legal for a class declared within a method (a method-local inner class). These rules differ from those for member and top-level classes.

Given Data / Assumptions:

• A method-local inner class is declared inside a method body.
• It is implicitly associated with the enclosing instance at runtime.

Concept / Approach:
Method-local inner classes cannot use access modifiers (public, private, protected) or static. They are implicitly non-static. However, they may be declared abstract or final (depending on design). The important takeaway: abstract is allowed; public and static are not.

Step-by-Step Reasoning:

Verification / Alternative check:
Try compiling examples with each modifier to see which are accepted by the Java compiler.

Why Other Options Are Wrong:

• "Must be marked final" is false; final is optional.
• "public" and "static" are illegal for method-local classes.

Common Pitfalls:
Assuming all inner classes can be static or use access modifiers; the rules depend on where the class is declared.

Final Answer:
It can be marked abstract.