Java — Create an anonymous inner class instance within a subclass method: class Boo { Boo(String s) { } Boo() { } } class Bar extends Boo { Bar() { } Bar(String s) { super(s); } void zoo() { // insert code here } }

Introduction / Context:
This question focuses on valid anonymous inner class creation expressions and constructor usage in inheritance hierarchies.

Given Data / Assumptions:

• Boo has two constructors: Boo() and Boo(String).
• Bar extends Boo and has Bar() and Bar(String) calling super(s).
• We are inside Bar.zoo().

Concept / Approach:
An anonymous inner class can extend a concrete class or implement an interface. The syntax is new Type(args) { /* body */ }. The constructor arguments must match an existing constructor. The resulting instance type is an anonymous subclass of the specified type.

Step-by-Step Solution:

Verification / Alternative check:
Also valid would be Boo f = new Boo() { }; using Boo's no-arg constructor, but that option is not provided exactly as such.

Why Other Options Are Wrong:
They either use non-existent constructors or incorrect syntax for anonymous classes.

Common Pitfalls:
Supplying wrong constructor arguments for the chosen type, and confusing anonymous subclassing with named nested classes.

Final Answer:
Boo f = new Bar() { };