Java — Identify which statements actually construct an anonymous inner class instance (Runnable example)

Introduction / Context:
This checks syntax for anonymous inner classes that implement an interface. For interfaces, you must provide implementations of all abstract methods in the anonymous body.

Given Data / Assumptions:

• Runnable has a single abstract method run().
• Anonymous class syntax is new InterfaceName() { /* implement methods */ }.

Concept / Approach:
Anonymous inner class creation expressions both instantiate and define a subclass or an implementation on the spot. If the target type is an interface, the body must implement all abstract methods.

Step-by-Step Solution:

Verification / Alternative check:
Assign the expression in D to a variable: Runnable r = new Runnable() { public void run() {} }; This compiles and constructs an anonymous class.

Why Other Options Are Wrong:
They violate required syntax or omit the mandatory run() implementation.

Common Pitfalls:
Forgetting parentheses after the type name and forgetting to implement abstract methods in the anonymous body.

Final Answer:
System.out.println(new Runnable() {public void run() { }});