Check if Array is Sorted in Java

Checking if an array is sorted is a basic and commonly asked question in Java interviews. In this post, we’ll check if an array is sorted in ascending or descending order using simple logic.

🧠 Approach

We iterate through the array and compare each element with the next one:

  • If all elements follow the order: arr[i] <= arr[i+1], then it's ascending.
  • If all elements follow: arr[i] >= arr[i+1], then it's descending.
  • Otherwise, it's unsorted.

✅ Java Program


public class CheckArraySorted {
    public static void main(String[] args) {
        int[] arr = {1, 3, 5, 7, 9};

        if (isSortedAscending(arr)) {
            System.out.println("Array is sorted in ascending order.");
        } else if (isSortedDescending(arr)) {
            System.out.println("Array is sorted in descending order.");
        } else {
            System.out.println("Array is not sorted.");
        }
    }

    static boolean isSortedAscending(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++) {
            if (arr[i] > arr[i + 1]) {
                return false;
            }
        }
        return true;
    }

    static boolean isSortedDescending(int[] arr) {
        for (int i = 0; i < arr.length - 1; i++) {
            if (arr[i] < arr[i + 1]) {
                return false;
            }
        }
        return true;
    }
}

✅ Output

Array is sorted in ascending order.

💡 Tip

This program can be modified to work with float, double, or even String arrays using appropriate comparison logic.

📌 Conclusion

We learned how to check if an array is sorted in Java without using any built-in methods. This is useful in many scenarios like optimization, binary search, or validating input data.