獲取下一個英文字母java

參考網址：http://blog.csdn.net/earbao/article/details/47615939

private String getNextUpEn(String en){
		if(en==null || en.equals(""))
			return "A";
	    char lastE = 'Z';
	    int lastEnglish = (int)lastE;    
	    char[] c = en.toCharArray();
	    if(c.length>1){
	    	return null;
	    }else{
	    	int now = (int)c[0];
	    	if(now >= lastEnglish)
	    		return null;
	    	char uppercase = (char)(now+1);
	    	return String.valueOf(uppercase);
	    }
	}