Determining the Type of a Character
You should use the methods in the class Character to determine the properties of a character. These methods work for the entire Unicode character set. 

 
 char ch = 'a';
 
 if (Character.isLetter(ch)) {
 } else if (Character.isDigit(ch)) {
 } else if (Character.isLowerCase(ch)) {
 } else if (Character.isUpperCase(ch)) {
 }
 // See Character for more methods.