Given the following Java code: public class CheckIt { public static void main (String[] args) { if (doCheck()) { System.out.print("square "); } System.out.print("..."); } public static int doCheck()…

The correct answer is C. An exception is thrown at runtime. The provided answer key appears to contain an error - the actual correct answer is B (Compilation fails). In Java, an if statement requires a strictly boolean expression; unlike C/C++, Java does not allow implicit conversion from int to boolean. Since doCheck() returns int, the…

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Question

Given the following Java code:
public class CheckIt {
public static void main (String[] args) {
if (doCheck()) {
System.out.print("square ");
}
System.out.print("...");
}
public static int doCheck() {
return 0;
}
}
What is the result?

Options

ASquare ...
BCompilation fails.
CAn exception is thrown at runtime.
D...

How the community answered

(42 responses)

A
2% (1)
C
93% (39)
D
5% (2)

Explanation

The provided answer key appears to contain an error - the actual correct answer is B (Compilation fails).

In Java, an if statement requires a strictly boolean expression; unlike C/C++, Java does not allow implicit conversion from int to boolean. Since doCheck() returns int, the line if (doCheck()) produces a compile-time error: "incompatible types: int cannot be converted to boolean." No bytecode is ever generated, so a runtime exception (C) is impossible - the program never runs.

A is wrong because the code never compiles, let alone prints anything.
C is wrong because the error is caught by the compiler, not at runtime.
D is wrong for the same reason as A - no output is produced.

Memory tip: In Java, if is not C - remember "Java demands boolean, period." Any time you see a non-boolean type (int, Integer, Object) used directly in an if condition without an explicit comparison (== 0, != null, etc.), your first instinct should be compilation failure.

Topics

#type_mismatch#if_statement#boolean_expression#type_compatibility

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