How to Resolve Stack Overflow Errors in Quicksort Java Implementation?

How can I fix stack overflow errors when implementing the Quicksort algorithm in Java?

public void quicksort(int[] array, int low, int high) {
    if (low < high) {
        int pi = partition(array, low, high);
        quicksort(array, low, pi - 1);
        quicksort(array, pi + 1, high);
    }
}

Stack overflow errors in a Quicksort implementation commonly arise from excessive recursion. This occurs when the depth of the recursive calls exceeds the Java virtual machine's stack size. Understanding how to optimize recursion for Quicksort can help you avoid these issues and ensure your sorting algorithm runs efficiently.

public void quicksortIterative(int[] array) {
    int[] stack = new int[array.length];
    int top = -1;
    stack[++top] = 0;
    stack[++top] = array.length - 1;
    while (top >= 0) {
        int high = stack[top--];
        int low = stack[top--];
        int pi = partition(array, low, high);
        if (pi - 1 > low) {
            stack[++top] = low;
            stack[++top] = pi - 1;
        }
        if (pi + 1 < high) {
            stack[++top] = pi + 1;
            stack[++top] = high;
        }
    }
}

Causes

• Deep recursion due to poor pivot selection
• Recursion on already sorted or nearly sorted data
• Improper base case handling in the recursion

Solutions

• Implement a hybrid approach using iteration and recursion
• Use tail call optimization to reduce stack depth
• Choose a better pivot (like median-of-three) to minimize recursion depth
• Switch to an iterative method for sorting smaller subarrays

Mistake: Using a bad pivot leading to unbalanced partitions.

Solution: Implement median-of-three or random pivot selection.

Mistake: Not handling base cases correctly which results in infinite recursion.

Solution: Ensure base cases are clearly defined before the recursive calls.

Mistake: Recursing on an already sorted array leading to deep recursion.

Solution: Use a threshold to switch to insertion sort for small arrays.