Simple java array string algorithms question

My two functions isSorted and hasDuplicate created below should work, right? My test class for the assignment wasn't working. The instructions for both are in the comments below. isSorted returns true if the string array is sorted alphabetically, and false - if not. hasDuplicate returns true if there's at least one set of duplicate strings and false - if not.

public class CheckStrings {
	/**
	 * Returns true if the Strings in w appear in sorted order
	 * (alphabetical order) and false otherwise.
	 * 
	 * @param w the array of Strings to check
	 * @return true if the Strings in w appear in sorted order
	 * and false otherwise.
	 */
	public static boolean isSorted(String[] w) {
		boolean bob = true;
		for (int i = 0; i < w.length-1; i++)
		{
			if (w[i].compareTo(w[i+1]) >= 0)
			{
				bob = true;
			}
			else
			{
				bob = false;
				i = w.length + 50;
			}
		}
		
		return bob;
	}
	
	/**
	 * Returns true if at least one String in w appears more than once
	 * and false otherwise.
	 * 
	 * @param w the array of Strings to check
	 * @return true if at least one String in w appears more than once
	 * and false otherwise.
	 */
	public static boolean hasDuplicate(String[] w) {
		boolean bob = true;
		for (int i = 0; i < w.length-1; i++)
		{
			if (w[i].equals(w[i+1]))
			{
				bob = true;
				i = w.length + 50;
			}
			else
			{
				bob = false;
				
			}
		}
		return bob;
	}
}

Submit this for your homework:

public static boolean isSorted(String[] w) {
return Arrays.stream(w).reduce("",(a, b) -> a == null || a.compareTo(b) > 0 ? null : b) != null;
}
public static boolean hasDuplicate(String[] w) {
return Arrays.stream(w).distinct().count() == w.length;
}

And who is Bob?

public final class CheckStrings {
private CheckStrings() {
}
public static boolean isSorted(String... w) {
if (w == null || w.length == 0)
return false;
for (int i = 0, j = w.length - 1; j < w.length; i++, j++)
if (w[i].compareToIgnoreCase(w[j]) > 0)
return false;
return true;
}
public static boolean hasDuplicate(String... w) {
if (w == null || w.length == 0)
return false;
Set<String> unique = new HashSet<>();
for (String str : w)
if (!unique.add(str.toLowerCase()))
return false;
return true;
}
}

Output:

String[] arr = {"a", "a", "b", "b", "c", "c"};
System.out.println(CheckStrings.isSorted(arr));     // true
System.out.println(CheckStrings.hasDuplicate(arr)); // true

In case you're not allowed yet to use Java 8 Stream API, implementation of the isSorted and hasDuplicate may look as follows:

public static boolean isSorted(String[] w) {
    if (null == w || w.length == 0) {
        return false;
    }

    for (int i = 0; i < w.length-1; i++) {
        if (w[i].compareTo(w[i+1]) > 0) {  // or compareToIgnoreCase if case insensitive is ok
            return false;
        }
    }
        
    return true;
}

public static boolean hasDuplicate(String[] w) {
    if (null == w || w.length < 2) return false;
        
    Set<String> set = new HashSet<>();
    for (int i = 0; i < w.length-1; i++) {
        String s = w[i];        // if case-insensitive lookup needed use s = w[i].toLowerCase();
        if (set.contains(s)) {
            return true;
        }
        set.add(s);
    }
    return false;
}

</details>