Why Java Character.toUpperCase/toLowerCase has no Locale parameter like String.toUpperCase/toLowerCase

Question

I am wondering that why Character.toUpperCase/toLowerCase has no Locale parameter like String.toUpperCase/toLowerCase.

I have to first uppercase of a text that can be in Any language. I have 2 solutions:

1. Use Character.toUpperCase

   String text = "stack overflow";
   StringBuilder sb = new StringBuilder(text);   
   
   sb.setCharAt(0, Character.toUpperCase(sb.charAt(0))); // No Locale parameter here.
   
   String out = sb.toString(); //Out: Stack overflow
   

2. Use String.toUpperCase

   Locale myLocale = new Locale(locateId);
   
   String text = "stack overflow";
   String text1 = text.substring(0,1).toUpperCase(myLocale );
   String text2 = text.substring(1);
   
   String out = text1 + text2; // Out: Stack overflow
   

For my Locale. Both way has the same result.

My question is:

• Since the text can be in any language. Which way should I use?

• Why Character.toUpperCase/toLowerCase has no Locale parameter because there is not much difference between Character.toUpperCase/toLowerCase and String.toUpperCase/toLowerCase because String is array of Characters.

Answer 1

From the Character#toUpperCase(int) Javadoc,

In general, String.toUpperCase() should be used to map characters to uppercase. String case mapping methods have several benefits over Character case mapping methods. String case mapping methods can perform locale-sensitive mappings, context-sensitive mappings, and 1:M character mappings, whereas the Character case mapping methods cannot.

So, the answer is your second example (String.toUpperCase)