i want to take explain #1520

Sasha1256 · 2024-11-28T15:13:12Z

No description provided.

mateacademy-ai-mentor

Thank you for your hard work on this pull request! 😊 While you've made a great effort, there are a few critical issues that need to be addressed to ensure the functionality and reliability of the ArrayList implementation:

Index Validation: The conditions in checkIndexforAdd and checkIndex methods are incorrect. For adding, the condition should allow adding at the end of the list (index <= count), and for accessing/removing, it should be index < count.
Array Resizing and Shifting: The add method does not correctly handle array resizing and element shifting. This can lead to incorrect data placement and potential data loss.
addAll Method: This method does not check if the current array has enough capacity to add all elements from the list, which can lead to array out-of-bounds errors.
Element Removal Logic: The remove method should iterate over the elements array to find and remove the specified element, not a temporary array.
Redundant and Incorrect Code: There are redundant lines and incorrect loop boundaries that need to be corrected to prevent logical errors and improve code clarity.
Use of Utility Classes: The use of Arrays.copyOf() violates the constraint of not using utility classes, which is critical to address.

Please address these issues to ensure the code meets the core requirements and functions as expected. Once these changes are made, I look forward to approving your improved solution! Keep up the great work, and don't hesitate to reach out if you need any help. 🚀

✨ Please rate this review in the Platform's notification center. I will be grateful for your feedback! ✨

🔄 Fix the issues, commit the changes, and then re-request my review using the Re-request review button in the Reviewers tab.

mateacademy-ai-mentor · 2024-11-28T15:14:03Z

src/main/java/core/basesyntax/ArrayList.java


    }

    @Override
    public void add(T value, int index) {
+        checkIndexforAdd(index);
+        count++;
+        Object[] newArray = new Object[MAX_CAPACITY];


The newArray should be initialized with the current size of elements plus one, not MAX_CAPACITY. This ensures that the array can accommodate the new element.

mateacademy-ai-mentor · 2024-11-28T15:14:03Z

src/main/java/core/basesyntax/ArrayList.java

+        for (int i = 0; i < newArray.length; i++) {
+            if (i == index) {
+                break;
+            }
+            newArray[i] = elements[i];
+        }


The loop should iterate only up to count, not newArray.length, to avoid accessing uninitialized elements.

mateacademy-ai-mentor · 2024-11-28T15:14:03Z

src/main/java/core/basesyntax/ArrayList.java

+        for (int i = index + 1; i < newArray.length; i++) {
+            newArray[i] = elements[i - 1];
+        }


The loop should iterate from index to count, not newArray.length, to correctly shift elements after the insertion point.

mateacademy-ai-mentor · 2024-11-28T15:14:03Z

src/main/java/core/basesyntax/ArrayList.java

+            newArray[i] = elements[i - 1];
+        }
+        elements = newArray;
+        elements[index] = value;


This line is redundant because newArray[index] = value; has already been set. It should be removed.

mateacademy-ai-mentor · 2024-11-28T15:14:03Z

src/main/java/core/basesyntax/ArrayList.java

+        for (int i = 0; i < elements.length; i++) {
+            elements[i] = list.get(i);
+        }


The addAll method should check if the current array has enough capacity to add all elements from the list. If not, it should grow the array accordingly.

mateacademy-ai-mentor · 2024-11-28T15:14:03Z

src/main/java/core/basesyntax/ArrayList.java

+        for (int i = 0; i < newArray1.length; i++) {
+            if (newArray1[i] == element || (element != null
+            && element.equals(newArray1[i]))) {
+                a = i;
+                result = element;
+                thisExist++;
+                break;
+            }
+            newArray1[i] = elements[i];
+        }


The loop should iterate over elements, not newArray1, to find the element to remove. This will ensure that the correct element is found and removed.

mateacademy-ai-mentor · 2024-11-28T15:14:04Z

src/main/java/core/basesyntax/ArrayList.java

+    }
+
+    private void checkIndexforAdd(int index) {
+        if (index < 0 || index >= count) {


The condition should be index < 0 || index > count to allow adding at the end of the list (i.e., at count).

mateacademy-ai-mentor · 2024-11-28T15:14:04Z

src/main/java/core/basesyntax/ArrayList.java

+    }
+
+    private void checkIndex(int index) {
+        if (index < 0 || index > count) {


The condition should be index < 0 || index >= count to correctly validate existing indices.

mateacademy-ai-mentor

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mateacademy-ai-mentor

Review Summary

Great effort on implementing the ArrayList! 🎉 However, there are several critical issues that need attention to ensure the functionality and adherence to constraints:

Use of Utility Classes: The grow method uses Arrays.copyOf(), which violates the constraint of not using utility classes. Implement the array copying manually.
Array Resizing and Shifting: The add method needs to correctly handle array resizing and element shifting. Ensure the logic for growing the array and shifting elements is properly separated and implemented.
addAll Method: Ensure the current array has enough capacity to add all elements from the list by resizing appropriately before adding elements.
Element Removal Logic: The remove method should not create a new array each time an element is removed. Instead, shift elements within the existing array to maintain efficiency.
Index Validation: The checkIndexforAdd method should allow adding at the end of the list, and the set method should use checkIndex instead.
Loop Boundaries: Correct the loop boundaries in methods like addAll and grow to ensure proper functionality.
Informative Exception Messages: Include informative messages in exceptions to clarify what went wrong.

These issues are crucial for the correct functionality of your ArrayList. Addressing them will greatly improve your code. Keep up the good work, and use this opportunity to learn and enhance your coding skills! 🚀

✨ Please rate this review in the Platform's notification center. I will be grateful for your feedback! ✨

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java

@@ -1,48 +1,139 @@
 package core.basesyntax;

+import java.util.Arrays;


The use of Arrays.copyOf() in the grow method violates the constraint of not using utility classes. You should implement array copying manually.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java


    }

    @Override
    public void add(T value, int index) {
+        checkIndexforAdd(index);


The checkIndexforAdd method should allow adding at the end of the list, which means the condition should be index <= count.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java

+        checkIndexforAdd(index);
+        count++;
+        Object[] newArray = new Object[elements.length + 1];
+        if (count > MAX_CAPACITY) {


The condition count > MAX_CAPACITY is incorrect for determining when to grow the array. It should be count >= elements.length.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java

+             newArray = grow();
+
+        }
+        for (int i = 0; i < newArray.length; i++) {


The loop should iterate over elements.length instead of newArray.length to correctly copy elements up to the specified index.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java


    }

    @Override
    public void addAll(List<T> list) {
+        if (count > elements.length) {


The condition count > elements.length is incorrect for determining when to grow the array. It should be count + list.size() > elements.length to ensure there is enough space for all elements.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java

+        if (count > elements.length) {
+            elements = grow();
+        }
+        for (int i = 0; i < elements.length; i++) {


The loop should iterate over list.size() instead of elements.length to correctly add all elements from the list.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java

    }

    @Override
    public void set(T value, int index) {
-
+        checkIndexforAdd(index);


The checkIndexforAdd method is incorrectly used here. The set method should use checkIndex instead, as it is not adding a new element but replacing an existing one.

mateacademy-ai-mentor · 2024-11-28T16:40:46Z

src/main/java/core/basesyntax/ArrayList.java

-        return null;
+        checkIndex(index);
+        T element = (T) elements[index];
+        Object[] newArray1 = new Object[elements.length - 1];


Creating a new array with elements.length - 1 is incorrect. The array should remain the same size, and elements should be shifted to fill the gap left by the removed element.

mateacademy-ai-mentor · 2024-11-28T16:40:47Z

src/main/java/core/basesyntax/ArrayList.java

    }

    @Override
    public T remove(T element) {
-        return null;
+        T result = null;
+        Object[] newArray1 = new Object[elements.length - 1];


Similar to the remove(int index) method, creating a new array with elements.length - 1 is incorrect. The array should remain the same size, and elements should be shifted to fill the gap left by the removed element.

mateacademy-ai-mentor · 2024-11-28T16:40:47Z

src/main/java/core/basesyntax/ArrayList.java

+    }
+
+    public Object[] grow() {
+        return Arrays.copyOf(elements, MAX_CAPACITY + (MAX_CAPACITY >> 1));


The grow method should not use Arrays.copyOf(). Implement the array copying manually to adhere to the constraint of not using utility classes.

i want to take explain

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mateacademy-ai-mentor suggested changes Nov 28, 2024

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Sasha1256 requested a review from mateacademy-ai-mentor November 28, 2024 15:32

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i want to take explain

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Sasha1256 requested a review from mateacademy-ai-mentor November 28, 2024 15:40

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i want to take explain #1520

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		@@ -1,48 +1,139 @@
		package core.basesyntax;

		import java.util.Arrays;

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i want to take explain #1520

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