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Thread: String class: using the substring method to obtain only the last character in the str

  1. #1
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    Question String class: using the substring method to obtain only the last character in the str

    Given a string, return a new string where the first and last chars have been exchanged.

    frontBack("code") → "eodc"
    frontBack("a") → "a"
    frontBack("ab") → "ba"

    [FONT="Courier New"]public String frontBack(String str)
    {
      String firstLetter = str.substring(0,1);
      String lastLetter = str.substring([B]str.length - 1[/B, str.length); //is that valid?..
    }[/FONT]


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: String class: using the substring method to obtain only the last character in the

    Use a substring on the middle section of the string, and just use charAt to get the starting/ending characters for swapping (note: this code needs to be modified so it will check to see if the string has one or less characters, otherwise it will fail)

    String flipped = str.charAt(str.length()) + str.subString(1,str.length() - 1) + str.charAt(0);

    Substring works like this:
    The first parameter is the index of the character to include. The second parameter is the index of the character to stop before (this character is not included).

    ex:
    String str = "0123456789";
    System.out.println(str.substring(2,4));  // will printout "23"

  3. The Following User Says Thank You to helloworld922 For This Useful Post:

    etidd (February 4th, 2010)

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