个回答

• 慕仰6620973

  2016-07-23 20:15:43

  已采纳

     String temp = "哇哈哈";
     System.out.println(temp+"1234");    // 两个空间，分别是temp和temp+"1234"
     StringBuilder sb = new StringBuilder("哇哈哈");
     System.out.println(sb.append("1234"));  // 一个空间

  3

• Z华L

  2018-06-12 00:14:30

  有点理解了,一个相当于在原来的位置旁边接着写,另一个相当于把原来的擦掉重写.

  0

• dyr

  2016-07-23 20:34:23

  delete(int start, int end)

  Removes the characters in a substring of this sequence.

  replace(int start, int end, String str)

  Replaces the characters in a substring of this sequence with characters in the specified String.

  
  

  0