标识符命名

public class demo {
    public static void main(String[] args) {

        String Hello = "FukcU";     //标识符大小写敏感
        String hello = "FukcU";     //标识符首字母应该以字母
        String ahello = "FukcU";    //
        String Ahello = "FukcU";    //
        String _hello = "FukcU";    //下划线
        String $hello = "FukcU";    //美元符$开始
        //String 1hello = "FukcU";  //不能以数字
        //String #hello = "FukcU";  //或其他符号开始
        //String *hello = "FukcU";  //首字符之后可以使字母美元符下划线或数字的任意字符组合