1Z0-811 Arrays and Methods Practice Question
Given an array arr of length 5, which code snippet correctly creates a copy using System.arraycopy?
⚠ Common exam trap
Oracle often tests the requirement to use a specific method name exactly as stated in the question, so candidates mistakenly choose options that achieve the same result (like `Arrays.copyOf` or `clone()`) but do not use the mandated `System.arraycopy` call.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
int[] copy = new int[arr.length]; System.arraycopy(arr, 0, copy, 0, arr.length);
It first declares and initializes a destination array `copy` of the same length as `arr`, then calls `System.arraycopy(arr, 0, copy, 0, arr.length)` to copy all 5 elements from `arr` into `copy`. This is the only option that uses `System.arraycopy` correctly, as the method requires a pre-existing destination array.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
System.arraycopy(arr, 0, copy, 0, arr.length);
Why it's wrong here
copy is not declared or initialized.
- ✗
int[] copy = Arrays.copyOf(arr, arr.length);
Why it's wrong here
Uses Arrays.copyOf(), not arraycopy.
- ✓
int[] copy = new int[arr.length]; System.arraycopy(arr, 0, copy, 0, arr.length);
Why this is correct
Initializes copy then uses arraycopy correctly.
- ✗
int[] copy = arr.clone();
Why it's wrong here
Uses clone(), not arraycopy.
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