Given: public class Test { public static void main(String[] args) { final int x = 2; int y = x; while (y<3) { switch (y) { case 0+x: y++; case 1: y++; } } System.out.println(y); } } What is the…

Question

Options

• A4
• B2
• C6
• DNothing is printed because of an indefinite loop.
• ECompilation fails.
• F5
• GA runtime exception is thrown.
• H3

• A
  6% (2)
• C
  12% (4)
• D
  3% (1)
• E
  62% (21)
• G
  18% (6)

Explanation

There is an issue with this answer key. The stated correct answer E is actually incorrect per the Java Language Specification, and this is worth understanding precisely so you don't get tripped up.

Why E is wrong: final int x = 2 makes x a compile-time constant variable (JLS §4.12.4 - a final primitive initialized with a constant expression). Therefore case 0+x: is a valid compile-time constant expression equal to case 2:. The compiler evaluates it at compile time; this is not ambiguous.

What actually happens (correct answer: A - prints 4):

1. y = x = 2, while condition y < 3 is true, enter loop.
2. switch(2): matches case 0+x: (= case 2:), executes y++ → y=3.
3. No break, falls through to case 1:, executes y++ → y=4.
4. while(4 < 3) is false, exits. Prints 4.

Why each distractor is wrong:

• B/H (2/3): Ignores the fall-through from case 2 into case 1.
• D (infinite loop): y reaches 4 and exits normally.
• F/C (5/6): Fall-through only fires once per switch entry; y can't go past 4 here.
• G (runtime exception): Nothing here throws - no bad cast, null, or divide-by-zero.

Memory tip: When you see case expr: on an exam, ask two questions: (1) Is the expression a compile-time constant? (2) Are there duplicate case values? A final local variable initialized from a literal is a constant - this distinguishes final int x = 2 (valid in case) from int x = 2 (not valid).

Bottom line for exam prep: If this question appears on your actual exam and E is marked correct, the question itself has an error. The real trap being attempted here is testing whether you know final makes a variable usable in case labels - but the question accidentally has a valid constant expression, making E wrong.

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