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Review Summary
This is a solid attempt, but changes are needed due to a critical bug in the hashing logic that can cause a runtime error. Your current use of Math.abs(key.hashCode()) will fail if the key's hash code is Integer.MIN_VALUE, as Math.abs() will return a negative number, leading to an ArrayIndexOutOfBoundsException. A safer way to handle this is to use a bitwise operation to ensure the hash is always non-negative, for example: (key.hashCode() & 0x7fffffff) % table.length.
Additionally, please address two minor checklist violations:
- The resizing multiplier
2is a magic number and should be a named constant [CHECKLIST ITEM #2]. - The
Nodeconstructor'spublicaccess modifier is too broad for an inner class used only withinMyHashMap[CHECKLIST ITEM #6].
Once you fix the hashing bug and these minor points, your solution will be in great shape!
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Footnotes
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| private void resize() { | ||
| Node<K, V>[] oldTable = table; | ||
| table = (Node<K, V>[]) new Node[oldTable.length * 2]; |
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This violates checklist item #2: 'Any magic numbers should be constants'. The resizing factor 2 should be extracted into a named constant to improve readability and maintainability, for example, private static final int RESIZE_MULTIPLIER = 2;.
| return 0; | ||
| } | ||
| int hash = key.hashCode(); | ||
| return Math.abs(hash) % table.length; |
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This approach to handling negative hash codes has a subtle bug. Math.abs(Integer.MIN_VALUE) returns a negative value, which will cause the modulo operation to produce a negative index, leading to an ArrayIndexOutOfBoundsException. A safer way to ensure a non-negative result is to use a bitwise AND operation, like (hash & 0x7fffffff) % table.length.
| private V value; | ||
| private Node<K, V> next; | ||
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| public Node(K key, V value) { |
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This violates checklist item #6: 'If the method has only a utility purpose and is used only inside the same class, it should not be public'. Since the Node class is private and is only instantiated within MyHashMap, this constructor does not need public access. It can have private or default (package-private) access.
mateacademy-ai-mentor
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Review Summary
Excellent work on this iteration! I'm happy to approve your solution. You've successfully addressed all the feedback from the previous review, especially the critical hashing bug for Integer.MIN_VALUE. Replacing the magic numbers with named constants like GROW_FACTOR has also significantly improved readability. Your MyHashMap implementation is now robust, correct, and meets all the requirements. Well done!
✨ Please rate this review in the Platform's notification center1. I will be grateful for your feedback! ✨
Footnotes
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