Please find a sample code snippet :

import java.util.ArrayList;

public class ArrayListDemo {
    // Here is the code to check if array list is sorted in Ascending order or not
    boolean checkSorting(ArrayList< String > arraylist){
        boolean isSorted=true;
        for(int i=1;i < arraylist.size();i++){
            if(arraylist.get(i-1).compareTo(arraylist.get(i)) > 0){
                isSorted= false;
                break;
            }
        }
        return isSorted;
    }
    public static void main(String[] args) {
        ArrayList < String > al=new ArrayList < String >();
        al.add("abc");
        al.add("xyz");
        al.add("mnp");
        ArrayListDemo alDemo=new ArrayListDemo();
        System.out.println("Is Sorted in ascending:"+alDemo.checkSorting(al));

    }

}

Output: Is Sorted in ascending:false

1. public static boolean isSorted(int[] a) {
2. if (a == null || a. length <= 1) { return true;
3. return IntStream. range(0, a. length - 1). noneMatch(i -> a[i] > a[i + 1]); }
4. public static void main(String[] args) {
5. System. out. println(isSorted(a)); // true. }

You just need to write the below method in which you will pass your String Arraylist:

/**
 * This method will return false if you list is not sorted
 * @param list
 * @return
 */
public boolean isSorted(List<String> list)
{
    boolean sorted = true;        
    for (int i = 1; i < list.size(); i++) {
        if (list.get(i-1).compareTo(list.get(i)) > 0) sorted = false;
    }

    return sorted;
}

Hope this will help you :)