How i can exclude a string when using comparator

Question

Present i am using Comparator to sort my objects .I have the items in list as follows

   FIRST ITEM
   SECOND ITEM
   THIRD ITEM
   LAST ITEM
   FORTH ITEM

Comparator code is:

public static Comparator<PartyResultVO> sortData = new Comparator<PartyResultVO>()
{

     public int compare(VO vo1, VO vo2)
     return (vo1.getName()).compareTo(vo2.getName());
};

It is working perfectly to sort.But what i want is i need to put the item with name LAST ITEM at last.How i can exclude only that object and place at the end.Is there any way to do that.

Please help me.Thanks in advance...

PSR · Accepted Answer · 2013-05-19 02:02:28Z

5

You can just add special logic for that case:

public static Comparator<VO> sortData = new Comparator<VO>()
{
     public int compare(VO vo1, VO vo2) {
         if (vo1.getName().equals("LAST ITEM")) {
              if (vo2.getName().equals("LAST ITEM")) {
                  return 0;
              } else {
                  return 1;
              }
         else if (vo2.getName().equals("LAST ITEM")) {
              return -1;
         }
         return (vo1.getName()).compareTo(vo2.getName());
     }
};

edited May 19, 2013 at 2:02

PSR

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answered May 17, 2013 at 7:24

Keppil

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9 Comments

kennytm Over a year ago

Make sure comparing two "LAST ITEM"s return 0 though.

Keppil Over a year ago

@KennyTM: That doesn't matter when it comes to sorting, but it might be more complete to do it.

PSR Over a year ago

But i am not sure about the name exaclty.But it contains the word last

Peter Lawrey Over a year ago

On an unrelated note: I was in Keppil Way last week.

Peter Lawrey Over a year ago

@PSR You appears to be physically able to type contains so I assume so.

|

AllTooSir · Accepted Answer · 2013-05-17 07:28:17Z

2

Can you try this ?

Collections.sort(list, new Comparator<PartyResultVO>() {

@Override
public int compare(VO vo1, VO vo2) {
    if (vo1.getName().equals("LAST ITEM")) {
          if (vo2.getName().equals("LAST ITEM")) {
              return 0;
          } else {
              return 1;
          }
     else if (vo2.getName().equals("LAST ITEM")) {
          return -1;
     }
        return  vo1.getName().compareTo(vo2.getName());
    }


});

answered May 17, 2013 at 7:28

AllTooSir

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Comments

heikkim · Accepted Answer · 2013-05-17 07:32:44Z

2

You could introduce state to your comparator and make it work exceptionally with certain values, return an integer that guarantees it will be the last one. Extended example of Keppil's comparator:

class PartyResultComparator implements Comparator<PartuResultVO> {
    String exceptionalValue;

    public PartyResultComparator(String exceptionalValue) {
        this.exceptionalValue = exceptionalValue;
    }

    public int compare(VO vo1, VO vo2) {
         if (isExceptional(vo1.getName())) {
              return 1;
         else if (isExceptional(vo2.getName())) {
              return -1;
         }

         return (vo1.getName()).compareTo(vo2.getName());
    }

    private boolean isExceptional(String value) {
        // is this value exceptional?
    }
}

edited May 17, 2013 at 7:32

answered May 17, 2013 at 7:24

heikkim

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Comments

Peter Lawrey · Accepted Answer · 2013-05-17 07:32:44Z

0

A shorter implementation

public static Comparator<PartyResultVO> sortData = new Comparator<PartyResultVO>() {
     public int compare(VO vo1, VO vo2) {
         return mapToLast(vol.getName()).compareTo(mapToLast(vo2.getName()));
     }
    String mapToLast(String s) {
        return s.contains("LAST") ? "\uFFFF" : s;
    }
}

answered May 17, 2013 at 7:32

Peter Lawrey

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