e305. determining the type of a character.txt

这里面包含了一百多个JAVA源文件

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)) {      // true
    }
    if (Character.isDigit(ch)) {       // false
    }
    if (Character.isLowerCase(ch)) {   // true
    }
    if (Character.isUpperCase(ch)) {   // false
    }
    // See Character for more methods.