Java arrays default values: which four entries correctly describe default element values for the given types?
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A1, 2, 3, 4
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B1, 3, 4, 5
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C2, 4, 5, 6
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D3, 4, 5, 6
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ENone of these
Answer
Correct Answer: 1, 3, 4, 5
Explanation
Introduction / Context:When you create an array in Java, every element is automatically initialized to a type-specific default. This behavior differs for primitives and reference types.
Given Data / Assumptions:
- Types and proposed defaults: int → 0, String → ""null"" (string literal), Dog → null, char → '\u0000', float → 0.0f, boolean → true.
Concept / Approach:Java default element values: numeric primitives → 0/0.0, char → '\u0000', boolean → false, reference types → null (not the string ""null"").
Step-by-Step Solution:
int → 0 → correct.String → ""null"" → incorrect (should be null reference).Dog (reference) → null → correct.char → '\u0000' → correct (NUL code unit 0).float → 0.0f → correct.boolean → true → incorrect (default is false).Verification / Alternative check:Allocate new arrays and print default values; booleans print false, references print null.
Why Other Options Are Wrong:Any set that includes String → ""null"" or boolean → true is incorrect.
Common Pitfalls:Misunderstanding null vs. the string ""null""; assuming booleans default to true.
Final Answer:1, 3, 4, 5