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Thread: What does compareTo method of String do ?

  1. #1
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    Default What does compareTo method of String do ?

    Hi all,

    I am just working through all the methods for String in java.

    I am on compareTo at the moment but have to say i dont really know what it does, i have a small working program here to test it:

    package testing;
     
    import java.lang.String;
     
    public class testpage {
    public static void main(String[] args) { 
     
     
        String myString = "abcdef";
        String myStringTwo = "regkaneighuornag";
     
        int myInt = myString.compareTo(myStringTwo);
     
        System.out.println(myInt);
     
    }
    }


    And my result for myInt is: -17

    But what does this -17 actually mean ? Thanks. All java docs say is ''Compares two strings lexicographically."

    But i dont know what this is.


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    Super Moderator Norm's Avatar
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    Default Re: What does compareTo method of String do ?

    The API doc defines what the method returns.
    What definition did google give for: lexicographical

    Did you read the API doc for the method? It is explained there.
    Last edited by Norm; December 8th, 2012 at 03:19 PM. Reason: API doc explains
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: What does compareTo method of String do ?

    I was looking at 'Method Summary' I hadnt scrolled Down and seen all the ''Method Detail'' for each method.

    Anyhow, having read it, i understand it compares each index. My issue is why is it returning -17 when the longest string is of length 16.

    I would think it should be returning -16 at most, if no index's match up. ?

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    Super Moderator Norm's Avatar
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    Default Re: What does compareTo method of String do ?

    My issue is why is it returning -17
    Reread the API doc. Its explained there.
    Why go past the first character of the two Strings if they are different.
    Execute this:
    System.out.println('a'-'r');  //  compare first two characters
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: What does compareTo method of String do ?

    I understand it now, it compares the first one, if equal, moves to the next.

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    Default Re: What does compareTo method of String do ?

    Compares this instance with a specified object or String and returns an integer that indicates whether this instance precedes, follows, or appears in the same position in the sort order as the specified object or String.

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