Which Java class inherits its equals() and hashCode() directly from java.lang.Object (i.e., does not override them)?

Introduction / Context:
Many core Java classes override equals() and hashCode() to provide value-based equality. Others, notably mutable sequence classes, keep identity-based equality from Object. Recognizing which is which is a common exam topic.

Given Data / Assumptions:

• We compare several classes from java.lang.
• We must identify the one that does not override equals() and hashCode().

Concept / Approach:
String, Integer, Double, and Character are value types and override equals()/hashCode() to compare by content/value. StringBuffer, being a mutable buffer, inherits identity-based equality from Object, meaning two different buffers with the same characters are not considered equal unless they are the same instance.

Step-by-Step Reasoning:

Verification / Alternative check:
Printing new StringBuffer("a").equals(new StringBuffer("a")) yields false, confirming identity equality.

Why Other Options Are Wrong:
Each of them defines value-based equality and a corresponding hash code implementation.

Common Pitfalls:
Confusing StringBuffer with StringBuilder (neither overrides equals/hashCode) versus String which does.

Final Answer:
java.lang.StringBuffer