In Java programming, which of the following is a valid declaration of a String variable?

Question

Solve this multiple-choice question and choose the correct option.

Accepted Answer

Introduction / Context:Java treats java.lang.String as a reference type. A declaration must follow Java’s literal and casting rules. This question checks your understanding of valid String initializations and the difference between character literals, Unicode escapes, and reference nulls. Given Data / Assumptions: We are declaring String references in standard Java. Single quotes denote a single char literal, not a String. Unicode escapes like \uXXXX represent a single char code point when used inside character or string literals. Concept / Approach:A String variable may be assigned either a String object (e.g., a double-quoted literal) or the null reference. Casting a char to String is not legal without calling an API (such as Character.toString or String.valueOf). Single quotes are for char, not String. Step-by-Step Solution: Check option A: String s1 = null; → Valid; a reference can be null.Check option B: String s2 = 'null'; → 'null' is a char literal (and 4 chars are not allowed for char), invalid for String.Check option C: String s3 = (String) 'abc'; → Illegal cast; 'abc' would be invalid char literal and cannot be cast to String.Check option D: String s4 = (String) '\ufeed'; → A char literal with a Unicode escape cannot be cast to String directly. Verification / Alternative check:Compile the snippets individually; only option A compiles without extra helper methods. Why Other Options Are Wrong:They either misuse single quotes (char literal) or perform an invalid cast from char to String. Common Pitfalls:Confusing ' ' (char) with "" "" (String), and assuming casts can magically convert primitives to reference types. Final Answer:String s1 = null;

In Java programming, which of the following is a valid declaration of a String variable?

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