Comparator?

Discussion in 'Java' started by Knute Johnson, Dec 12, 2011.

  1. I've got a question about how to create a Comparator that I can use to
    keep a sorted list of objects. The sort fields would be a code that is
    not something to be sorted directly and a String that I would want
    alphabetical. I would have a list of the codes and that list would be
    in the sorted order. What I want to do is put the data in order
    according to the list of codes and the other String.

    The codes are actually going to be a 3 letter String. For example the
    codes could be;

    XAB
    AJC
    BQP
    RST

    and the data would be a code String and another String to sort
    alphabetically.

    XAB San Francisco
    BQP Alabama
    XAB Houston
    AJC Montreal

    I want the data sorted in this order:

    XAB Houston
    XAB San Francisco
    AJC Montreal
    BQP Alabama

    Any simple ideas on how to design the Comparator?

    Thanks,

    --

    Knute Johnson
    Knute Johnson, Dec 12, 2011
    #1
    1. Advertising

  2. Knute Johnson

    Roedy Green Guest

    On Sun, 11 Dec 2011 17:26:51 -0800, Knute Johnson
    <> wrote, quoted or indirectly quoted someone
    who said :

    >I've got a question about how to create a Comparator that I can use to
    >keep a sorted list of objects


    see http://mindprod.com/applet/comparatorcutter.html

    Just fill in the blanks and it will generate you the Java code you
    need.

    You could do thing with strings with the airport code in the first
    three slots or with objects with an airport and City name String
    field.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com
    For me, the appeal of computer programming is that
    even though I am quite a klutz,
    I can still produce something, in a sense
    perfect, because the computer gives me as many
    chances as I please to get it right.
    Roedy Green, Dec 12, 2011
    #2
    1. Advertising

  3. On 12/11/2011 6:16 PM, Patricia Shanahan wrote:
    > Knute Johnson wrote:
    >> I've got a question about how to create a Comparator that I can use to
    >> keep a sorted list of objects. The sort fields would be a code that is
    >> not something to be sorted directly and a String that I would want
    >> alphabetical. I would have a list of the codes and that list would be
    >> in the sorted order. What I want to do is put the data in order
    >> according to the list of codes and the other String.
    >>
    >> The codes are actually going to be a 3 letter String. For example the
    >> codes could be;
    >>
    >> XAB
    >> AJC
    >> BQP
    >> RST
    >>
    >> and the data would be a code String and another String to sort
    >> alphabetically.
    >>
    >> XAB San Francisco
    >> BQP Alabama
    >> XAB Houston
    >> AJC Montreal
    >>
    >> I want the data sorted in this order:
    >>
    >> XAB Houston
    >> XAB San Francisco
    >> AJC Montreal
    >> BQP Alabama
    >>
    >> Any simple ideas on how to design the Comparator?
    >>
    >> Thanks,
    >>

    >
    > I would deal with the codes by creating a Map<String,Integer>, and
    > initializing it to map each code to its index in the original list.
    >
    > In the compare method, first compare the results of looking up the codes
    > in the map. If that gives equality, then compare the city name strings
    > to resolve the comparison.
    >
    > Patricia


    Thanks very much Patricia.

    --

    Knute Johnson
    Knute Johnson, Dec 12, 2011
    #3
  4. On 12/12/2011 1:05 AM, Roedy Green wrote:
    > On Sun, 11 Dec 2011 17:26:51 -0800, Knute Johnson
    > <> wrote, quoted or indirectly quoted someone
    > who said :
    >
    >> I've got a question about how to create a Comparator that I can use to
    >> keep a sorted list of objects

    >
    > see http://mindprod.com/applet/comparatorcutter.html
    >
    > Just fill in the blanks and it will generate you the Java code you
    > need.
    >
    > You could do thing with strings with the airport code in the first
    > three slots or with objects with an airport and City name String
    > field.


    Thanks Roedy, I'll take a look.

    --

    Knute Johnson
    Knute Johnson, Dec 12, 2011
    #4
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Valentin Tihomirov

    flags vs. comparator

    Valentin Tihomirov, Nov 10, 2003, in forum: VHDL
    Replies:
    5
    Views:
    626
    Valentin Tihomirov
    Nov 11, 2003
  2. sunil
    Replies:
    4
    Views:
    766
    Ralf Hildebrandt
    Feb 22, 2004
  3. sk

    comparator problem

    sk, Nov 3, 2004, in forum: VHDL
    Replies:
    0
    Views:
    843
  4. john

    counter plus comparator

    john, Nov 8, 2004, in forum: VHDL
    Replies:
    4
    Views:
    762
    Raghavendra
    Nov 10, 2004
  5. Replies:
    6
    Views:
    502
Loading...

Share This Page