替换 replace(oldchar,newchar)//单个字符替换
        replace(oldString,newString)//部分子串替换
切割split(regex);
      String s = "China，USA,Russia,Japan";
      String[] arr = s.split(",");

替换 replace(oldchar,newchar)//单个字符替换
        replace(oldString,newString)//部分子串替换
切割split(regex);
      String s = "China，USA,Russia,Japan";
      String[] arr = s.split(",");