Added methods#1768
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Review Summary
I am requesting a few changes before this can be approved. You've done a great job implementing the core functionality of the ArrayList, and the exception handling is correct. However, there are a couple of key requirements from the task checklist that need to be addressed.
First, the index validation logic is repeated in several methods. Please extract this into a single private helper method to avoid code duplication [CHECKLIST ITEM #5]. Second, the task requires using System.arraycopy() for all array element manipulation. Your implementation currently uses for loops for shifting elements when adding or removing, and for copying the array when resizing. Please replace these loops with System.arraycopy() [CHECKLIST ITEM #8].
Once these changes are made, your solution will be in great shape. Keep up the good work!
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Footnotes
| for (int i = size; i > index; i--) { | ||
| elements[i] = elements[i - 1]; | ||
| } |
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This for loop is used to shift elements. This violates checklist item #8, which requires using System.arraycopy() to move array elements for better performance and to follow the project's guidelines.
| if (index < 0 || index >= size) { | ||
| throw new ArrayListIndexOutOfBoundsException( | ||
| "Index: " + index + ", Size: " + size | ||
| ); | ||
| } |
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This index-checking logic is repeated in the set() method (lines 63-66) and the remove(int) method (lines 74-76). This violates checklist item #5: 'Don't create repeating code.' Please extract this common logic into a single private helper method.
| T removed; | ||
| removed = (T) elements[index]; |
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The variable removed is declared on one line and initialized on the next. This can be combined into a single statement: T removed = (T) elements[index];. This violates checklist item #7 regarding redundant variables, which advises against code patterns that make the implementation less concise.
| for (int i = index; i < size - 1; i++) { | ||
| elements[i] = elements[i + 1]; | ||
| } |
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This for loop is used to shift elements after a removal. According to checklist item #8, you should use System.arraycopy() for this operation.
| for (int i = 0; i < elements.length; i++) { | ||
| newArray[i] = elements[i]; | ||
| } |
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This loop copies elements from the old array to the new one. This violates checklist item #8, which requires using System.arraycopy() for copying array elements.
mateacademy-ai-mentor
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Review Summary
Great job on this task! I am approving your solution as you've successfully implemented all the core requirements and addressed the previous feedback effectively. Your use of System.arraycopy and helper methods for index validation has made the code much cleaner.
While your solution is complete, here are a couple of suggestions for future improvement:
- In the
addAllmethod, you can make it more efficient by calculating the total required capacity once and resizing the array a single time, rather than potentially callinggrow()multiple times in a loop. - There's a small redundancy in the
remove(int index)method where the variable declaration and assignment can be combined into a single line:T removed = (T) elements[index];. [CHECKLIST ITEM #7]
These are optimizations and don't block the approval. Excellent work overall!
✨ Please rate this review in the Platform's notification center1. I will be grateful for your feedback! ✨
Footnotes
| if (list == null || list.isEmpty()) { | ||
| return; | ||
| } | ||
| while (size + list.size() > elements.length) { |
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This while loop can be inefficient if the list being added is large, as it might call grow() multiple times. A more optimal approach is to calculate the total required capacity once, perform a single resize if needed, and then add the new elements.
| T removed; | ||
| removed = (T) elements[index]; |
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This declaration and assignment can be combined into a single line to be more concise: T removed = (T) elements[index];. This addresses checklist item #7 about avoiding redundant variables.
| T removed = (T) elements[i]; | ||
| remove(i); | ||
| return removed; |
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There's a small redundancy here. The remove(i) method already retrieves and returns the element being removed. You can simplify these three lines into a single, more efficient line: return remove(i);. This avoids retrieving the same element twice.
| private void grow() { | ||
| int newCapacity = elements.length + (elements.length >> 1); | ||
| Object[] newArray = new Object[newCapacity]; | ||
| System.arraycopy(elements, 0, newArray, 0, elements.length); |
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When copying the array during a resize, you should only copy the elements that are actually in the list, which is determined by size. Using elements.length might copy unnecessary null values if the array isn't full. The correct length to copy is size.
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