⑴ int i = Integer.parseInt(String);

         ⑵ int i = Integer.valueOf(String);

         注：字符串轉換為Double, Float, Long類型用法類似

2.如何將int類型轉換為字符串

      ⑴   String  s = String.valueOf(int);

      ⑵   String  s = Integer.toString(int);

      ⑶   String s = " " + int;

        注：Double, Float, Long轉換為字符串類型用法類似