⑴ int i = Integer.parseInt(String);

         ⑵ int i = Integer.valueOf(String);

         注：字符串转换为Double, Float, Long类型用法类似

2.如何将int类型转换为字符串

      ⑴   String  s = String.valueOf(int);

      ⑵   String  s = Integer.toString(int);

      ⑶   String s = " " + int;

        注：Double, Float, Long转换为字符串类型用法类似