passed checkstyle and tests#1795
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Review Summary
This implementation has two critical violations of the task requirements that must be fixed before approval. First, the code imports and uses java.util.Arrays (line 3) and calls Arrays.copyOf() in the ensureCapacity() method, which explicitly violates the technical constraint 'Do not use Objects, Arrays, or any other util class.' You must replace this with a manual implementation using System.arraycopy() to create a new array and copy elements. Second, the constructor initializes the internal array with new Object[DEFAULT_CAPACITY], pre-allocating 10 elements. This differs from java.util.ArrayList behavior, which starts with an empty internal array—capacity 10 should only be allocated when the first element is added (lazy initialization). Please fix both issues and resubmit.
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Footnotes
| @@ -1,48 +1,119 @@ | |||
| package core.basesyntax; | |||
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| import java.util.Arrays; | |||
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This violates the technical constraint: 'Do not use Objects, Arrays, or any other util class.' The task explicitly prohibits using the Arrays class. Use System.arraycopy() to copy arrays instead of Arrays.copyOf().
| private int size; | ||
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| public ArrayList() { | ||
| this.elementData = new Object[DEFAULT_CAPACITY]; |
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According to the task requirements, the default capacity should match java.util.ArrayList behavior which starts with an EMPTY internal array. The capacity should become 10 only when the first element is added (via ensureCapacity logic), not pre-allocated in the constructor.
| : (int) (elementData.length * 1.5); | ||
| if (newLength < minCapacity) { | ||
| newLength = minCapacity; | ||
| } |
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Replace Arrays.copyOf() with a manual implementation using System.arraycopy() to avoid using the Arrays class. Create a new temporary array and copy elements manually.
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Review Summary
Your ArrayList implementation is approved and meets all requirements. The code successfully implements lazy initialization in the constructor (empty array created, capacity allocated only when needed), uses System.arraycopy() for array operations, and includes all required functionality: default capacity of 10 with 1.5x growth factor, proper exception handling for invalid indices and missing elements, and extracted helper methods for index validation and capacity management. All checklist items pass, and no test failures were reported. Great work addressing the previous review feedback!
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