In Java naming conventions and rules, which of the following statements are correct: (1) the first letter of a variable is lower case, (2) each subsequent word in the name begins with a capital letter, (3) all other letters are lower case, (4) a Java variable can start with a digit?

Introduction:
This question distinguishes between Java’s style conventions (camelCase for variables) and the syntactic rules enforced by the compiler (identifier formation). Understanding both prevents compile-time errors and improves code readability.

Given Data / Assumptions:

• (1) First letter lower case.
• (2) Each subsequent word begins with a capital letter (lower camelCase).
• (3) All other letters are lower case.
• (4) A variable can start with a digit.

Concept / Approach:

Java identifiers may contain letters, digits, underscores, and dollar signs, but must not start with a digit. Conventions recommend variables in lower camelCase: first word starts lower case; subsequent words are capitalized (e.g., totalAmount). While (3) is often true in practice, it is a stylistic simplification; camelCase typically keeps internal letters of non-leading words capitalized but can include digits or underscores when needed. Crucially, (4) contradicts Java’s rule that identifiers cannot begin with a digit.

Step-by-Step Solution:

Verification / Alternative check:

Compilation test: int 2count = 0; // errorint count2 = 0; // OK

Why Other Options Are Wrong:

'All' – includes (4), which is invalid. '1, 2, 4 only' and '2, 3, 4 only' both include the invalid (4).

Common Pitfalls:

Confusing conventions with rules; assuming digits can appear at the start; over-restricting names to letters only (digits and _/$ are permitted after the first character).

Final Answer:

1, 2, 3 only