TheAlgorithms/Java · error · IndexOutOfBoundsException

Position out of bounds

Error message

Position out of bounds

What it means

Thrown by CircularDoublyLinkedList.remove(int pos) when pos >= size or pos < 0. The list uses 0-based positions and the guard prevents walking past the sentinel/head node. Removing an out-of-range index would corrupt the circular linkage.

Source

Thrown at src/main/java/com/thealgorithms/datastructures/lists/CircularDoublyLinkedList.java:106

                sb.append(", ");
            }
            current = current.next;
        }
        sb.append(" ]");
        return sb.toString();
    }

    /**
     * Removes and returns the element at the specified position in the list.
     * Throws an IndexOutOfBoundsException if the position is invalid.
     *
     * @param pos the position of the element to remove
     * @return the value of the removed element - pop operation
     * @throws IndexOutOfBoundsException if the position is out of range
     */
    public E remove(int pos) {
        if (pos >= size || pos < 0) {
            throw new IndexOutOfBoundsException("Position out of bounds");
        }
        Node<E> current = head.next;
        for (int i = 0; i < pos; i++) {
            current = current.next;
        }
        current.prev.next = current.next;
        current.next.prev = current.prev;
        E removedValue = current.value;
        size--;
        return removedValue;
    }
}

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Check `pos >= 0 && pos < list.size()` before remove.
2. Guard the empty-list case explicitly.
3. Recompute the index or iterate in reverse when removing multiple elements.
4. Use strict `<` in loop bounds, never `<=` against size.

Example fix

// before
list.remove(pos); // pos may be stale

// after
if (pos >= 0 && pos < list.size()) {
    list.remove(pos);
}

if (pos >= 0 && pos < list.size()) {
    return list.remove(pos);
}

try {
    return list.remove(pos);
} catch (IndexOutOfBoundsException e) {
    // invalid pos
}

When it happens

Trigger: Calling remove on an empty list. Calling remove(size). Negative pos passed from an underflowed calculation.

Common situations: Index sourced from a different collection's size. Stale index held across prior removes. Off-by-one loop bound `i <= size`.

Related errors

• Position out of bounds
• Index: ${index}, Size: ${size}
• ${position}
• Cannot add null element to the list
• Cannot add null element to the list

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/e9fd494f2fe2a27d. Report an issue: GitHub.