Is there an existing library method that checks if a String is all upper case or lower case in Java?

Question

I know there are plenty of upper() methods in Java and other frameworks like Apache commons lang, which convert a String to all upper case.

Are there any common libraries that provide a method like isUpper(String s) and isLower(String s), to check if all the characters in the String are upper or lower case?

EDIT:

Many good answers about converting to Upper and comparing to this. I guess I should have been a bit more specific, and said that I already had thought of that, but I was hoping to be able to use an existing method for this.

Good comment about possible inclusion of this in apache.commons.lang.StringUtils. Someone has even submitted a patch (20090310). Hopefully we will see this soon. https://issues.apache.org/jira/browse/LANG-471

EDIT:

What I needed this method for, was to capitalize names of hotels that sometimes came in all uppercase. I only wanted to capitalize them if they were all lower or upper case. I did run in to the problems with non letter chars mentioned in some of the posts, and ended up doing something like this:

private static boolean isAllUpper(String s) {     for(char c : s.toCharArray()) {        if(Character.isLetter(c) && Character.isLowerCase(c)) {            return false;         }     }     return true; } 

This discussion and differing solutions (with different problems), clearly shows that there is a need for a good solid isAllUpper(String s) method in commons.lang

Until then I guess that the myString.toUpperCase().equals(myString) is the best way to go.

Answer 1

Now in StringUtils isAllUpperCase

Answer 2

Not a library function unfortunately, but it's fairly easy to roll your own. If efficiency is a concern, this might be faster than s.toUpperCase().equals(s) because it can bail out early.

public static boolean isUpperCase(String s) {     for (int i=0; i<s.length(); i++)     {         if (!Character.isUpperCase(s.charAt(i)))         {             return false;         }     }     return true; } 

Edit: As other posters and commenters have noted, we need to consider the behaviour when the string contains non-letter characters: should isUpperCase("HELLO1") return true or false? The function above will return false because '1' is not an upper case character, but this is possibly not the behaviour you want. An alternative definition which would return true in this case would be:

public static boolean isUpperCase2(String s) {     for (int i=0; i<s.length(); i++)     {         if (Character.isLowerCase(s.charAt(i)))         {             return false;         }     }     return true; }