In Java, which three are valid declarations for a float variable among the following candidates?

Introduction / Context:
Java's float is a 32-bit IEEE 754 type. Literal rules matter: decimal literals are double by default unless suffixed with F/f, whereas integer and hex integer literals can be assigned to float via widening conversion.

Given Data / Assumptions:

• Candidates: f1 = -343; f2 = 3.14; f3 = 0x12345; f4 = 42e7; f5 = 2001.0D; f6 = 2.81F.
• We check only compile-time validity without explicit casts.

Concept / Approach:
Rules: decimal floating-point literals are double unless suffixed F; assigning a double to float without cast is illegal. Integer literals (decimal/hex/octal) can widen to float. Scientific notation without F is double. Suffix D marks an explicit double literal.

Step-by-Step Solution:

Verification / Alternative check:
Adding explicit casts (e.g., (float)3.14) would make f2/f4/f5 compile, but the original forms do not.

Why Other Options Are Wrong:
They include at least one invalid assignment per the rules above.

Common Pitfalls:
Forgetting the F suffix for decimal float literals; assuming all numeric literals can be assigned without casts.

Final Answer:
1, 3, 6