Sorting ArrayList Objects.

>> Its really important.
Maybe you could have considered 500pts ;°)

Wait a minute... that's not OK...

Correction:

Collections.sort(list, new Comparator() {

     public int compare(Object o1, Object o2) {
          String s1 = (String)o1;
          String s2 = (String)o2;

          String integer1[] = s1.split("[^0-9]");      // <<<<<  changed
          String integer2[] = s2.split("[^0-9]");      // <<<<<  changed
          String chars1[] = s1.split("[0-9]+");         // <<<<<  changed
          String chars2[] = s2.split("[0-9]+");         // <<<<<  changed

          Integer i1 = new Integer( Integer.parseInt(integer1[0]) );
          Integer i2 = new Integer( Integer.parseInt(integer2[0]) );
   
          if (i1.equals(i2)
             return chars1[1].compareTo(chars2[1]);
          else
             return i1.compareTo(i2);
     }
});

I assumed that your list contains Strings like "115R", "1125R", "147C", "37R", "57R", "37C",...

zzynx is 100% correct that you should use a comparator, but you might find a simpler impelementation more readable.

I'm also not a big fan of anonymous inner class (they clutter the code something awful IMO).
 
Something like this would work just as well:

Collections.sort(list, new SpecialComarator());

Class SpecialComparator
implements Comparator
{
     public int compare(Object o1, Object o2)
    {
        String s1 = (String)o1;
        String s2 = (String)o2;

         int offset1 = findCharOffset(s1);
         int offset2 = findCharOffset(s2);

         int v1 = Integer.parseInt(s1.substring(0,offset1));
         int v2 = Integer.parseInt(s2.substring(0,offset2));

        int difference = v1 - v2;

        if (difference != 0)
        {
            return difference;
        }

        return s1.substring(offset1).compareTo(s2.substring(offset2));
    }

    private int findCharOffset(String value)
    {
        integer result = 0;
        while (result < value.length() && Character.isDigit(value.charAt(result))
        {
             result++;
        }

        return result;
    }
}

>> I'm also not a big fan of anonymous inner class
In this case I find an inner class is on it's place: It's here that you need the sorting; it's here that you find the Comparator class.
But, that's a matter of taste of course ;°)

>>...but you might find a simpler impelementation more readable.
Well, it's a matter of being/making yourself familiar with regular expressions.
In the past I also wasn't a big fan of them.
But once you discover their power...

Hi zzynx,

        Thank you for the quick response. I executed the code which shows the result as 1125R 115R 147C 37C 37R 57R. but I need the result as 37C 37R 57R 115R 147C 1125R. Can you help me with this.


Thanks.

Are you sure?
For me it just works:

        List list = new ArrayList();
        list.add("1125R");
        list.add("115R");
        list.add("147C");
        list.add("37C");
        list.add("37R");
        list.add("57R");
        Collections.sort(list, new Comparator() {

             public int compare(Object o1, Object o2) {
                  String s1 = (String)o1;
                  String s2 = (String)o2;

                  String integer1[] = s1.split("[^0-9]");      // <<<<<  changed
                  String integer2[] = s2.split("[^0-9]");      // <<<<<  changed
                  String chars1[] = s1.split("[0-9]+");         // <<<<<  changed
                  String chars2[] = s2.split("[0-9]+");         // <<<<<  changed

                  Integer i1 = new Integer( Integer.parseInt(integer1[0]) );
                  Integer i2 = new Integer( Integer.parseInt(integer2[0]) );

                  if (i1.equals(i2))
                     return chars1[1].compareTo(chars2[1]);
                  else
                     return i1.compareTo(i2);
             }});
        System.out.println("\nStrings sorted List ...");
        for(int i = 0; i < list.size(); i++) {
               System.out.println((String)list.get(i));
        }

Output:
Strings sorted List ...
37C
37R
57R
115R
147C
1125R

I'm going offline. Success.

>>>...but you might find a simpler impelementation more readable.
> Well, it's a matter of being/making yourself familiar with regular expressions.
> In the past I also wasn't a big fan of them.
> But once you discover their power...

Sure, regular expressions are powerful things and I know full well HOW to use them. I'm not conviced that they are the most appropriate solution in this case - they're TOO powerful and unnecessarily complicate an essentially simple problem.

An of course, that too is a matter of taste. I'm a card carrying member of "Do The Simplest Thing That Could Possibly Work".

Actually thinking about it more clearly, something like this would also work:

Class SpecialComparator
implements Comparator
{
     public int compare(Object o1, Object o2)
    {
        String s1 = (String)o1;
        String s2 = (String)o2;

         int v1 = Integer.parseInt(s1.substring(0,s1.length() - 1));
         int v2 = Integer.parseInt(s2.substring(0,s2.length() - 1));

        int difference = v1 - v2;

        if (difference != 0)
        {
            return difference;
        }

        return Character.getNumericValue(s1.charAt(length() - 1) -
                 Character.getNumericValue(s2.charAt(length() - 1);
    }

Hi,

     I am not getting the write output. I don't think this is working, but hey thanks for the response. I appreciate that.

Thanks.

>> I am not getting the write output
You mean with what I posted? Impossible. It just works for me!
It outputs:
37C
37R
57R
115R
147C
1125R

Can you show us the exact code you have for the moment? There must be something wrong with it...

Hi zzynx,
         
        Here is the exact code which I have. Please help me with this. Here is the arguments which I passed while executing 115R 1125R 147C 37R 57R 37C and I am getting the output as  1125R 115R 147C 37C 37R 57R. Below is the code:


import java.util.*;

public class SortObjects
{      
      public static void main(String s[])
      {  
            Collections col;
            List l = sort(s);
            
            System.out.println("\nStrings sorted List ...");
            for(int i = 0; i < s.length; i++)
            {
                  System.out.println((String)l.get(i));
            }
            
            int ints[] = {
                                    11, 2, -22, 401, 6
                                    };
            
            Integer in[] = new Integer[ints.length];            
            for(int i = 0; i < in.length; i++)
            {
                  in[i] = new Integer(ints[i]);
            }
            
            l = sort(in);
            System.out.println("\nIntegers sorted List ...");
            
            for(int i = 0; i < in.length; i++)
            {
                  System.out.println((Integer)l.get(i));
            }
    }
      
    public static List sort(Object o[])
    {
            ArrayList al = new ArrayList();
            for(int i = 0; i < o.length; i++)
            al.add(i, o[i]);
            List list = Collections.synchronizedList(al);
            
            Collections.sort(list, new Comparator()
            {

            public int compare(Object o1, Object o2)
            {
                                   
                  String s1 = (String)o1;
                String s2 = (String)o2;

                int v1 = Integer.parseInt(s1.substring(0,s1.length() - 1));
                int v2 = Integer.parseInt(s2.substring(0,s2.length() - 1));

                int difference = v1 - v2;

                if (difference != 0)
                {
                    return difference;
                }

                return Character.getNumericValue(s1.charAt(s1.length() - 1)) -
                         Character.getNumericValue(s2.charAt(s1.length() -1));
                  
            }
        });
      
            //Collections.sort(list , new SpecialComparator());
            
            System.out.println("\nStrings sorted List ...");
            
            for(int i = 0; i < list.size(); i++)                        
          System.out.println((String)list.get(i));
            
            return list;
    }
   
}


Thanks in advance.

hi,


    I have tried this code too.


/*
 * Created on Dec 10, 2004
 *
 * @author z688240
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */

import java.util.*;

public class SortObjects
{      
      public static void main(String s[])
      {  
            Collections col;
            List l = sort(s);
            
            System.out.println("\nStrings sorted List ...");
            for(int i = 0; i < s.length; i++)
            {
                  System.out.println((String)l.get(i));
            }
            
            int ints[] = {
                                    11, 2, -22, 401, 6
                                    };
            
            Integer in[] = new Integer[ints.length];            
            for(int i = 0; i < in.length; i++)
            {
                  in[i] = new Integer(ints[i]);
            }
            
            l = sort(in);
            System.out.println("\nIntegers sorted List ...");
            
            for(int i = 0; i < in.length; i++)
            {
                  System.out.println((Integer)l.get(i));
            }
    }
      
    public static List sort(Object o[])
    {
            ArrayList al = new ArrayList();
            for(int i = 0; i < o.length; i++)
            al.add(i, o[i]);
            List list = Collections.synchronizedList(al);
            
            Collections.sort(list, new Comparator()
            {

            public int compare(Object o1, Object o2)
            {
                 String s1 = (String)o1;
                 String s2 = (String)o2;

                 String integer1[] = s1.split("[^0-9]");      // <<<<<  changed
                 String integer2[] = s2.split("[^0-9]");      // <<<<<  changed
                 String chars1[] = s1.split("[0-9]+");         // <<<<<  changed
                 String chars2[] = s2.split("[0-9]+");         // <<<<<  changed

                 Integer i1 = new Integer( Integer.parseInt(integer1[0]) );
                 Integer i2 = new Integer( Integer.parseInt(integer2[0]) );

                 if (i1.equals(i2))
                    return chars1[1].compareTo(chars2[1]);
            }
        });
      
      
            System.out.println("\nStrings sorted List ...");
            
            for(int i = 0; i < list.size(); i++)                        
          System.out.println((String)list.get(i));
            
            return list;
    }
   
 
}

Hi sunny,
this should work (I felt free to remove all obsolete stuff):

/*
 * SortObjects.java
 *
 * Created on 13 december 2004, 8:47
 */

import java.util.*;

public class SortObjects
{    
     public static void main(String s[])
     {
        // The input is a String array. Make that an ArrayList:
        List inputList = new ArrayList(Arrays.asList(s));
       
        List l = sort(inputList);
         
        System.out.println("\nStrings sorted List ...");
        for(int i = 0; i < l.size(); i++)
            System.out.println((String)l.get(i));
    }
     
    public static List sort(List list) {
          Collections.sort(list, new Comparator() {

            public int compare(Object o1, Object o2) {
                 String s1 = (String)o1;
                 String s2 = (String)o2;

                 String integer1[] = s1.split("[^0-9]");      // <<<<<  changed
                 String integer2[] = s2.split("[^0-9]");      // <<<<<  changed
                 String chars1[] = s1.split("[0-9]+");         // <<<<<  changed
                 String chars2[] = s2.split("[0-9]+");         // <<<<<  changed

                 Integer i1 = new Integer( Integer.parseInt(integer1[0]) );
                 Integer i2 = new Integer( Integer.parseInt(integer2[0]) );

                 if (i1.equals(i2))
                    return chars1[1].compareTo(chars2[1]);
                  else
                     return i1.compareTo(i2);
            }
        });
        return list;
    }
}

But in fact, I wouldn't even make that a separate function:

/*
 * SortObjects.java
 *
 * Created on 13 december 2004, 8:47
 */

import java.util.*;

public class SortObjects
{    
     public static void main(String s[])
     {
        // The input is a String array. Make that an ArrayList:
        List inputList = new ArrayList(Arrays.asList(s));
       
        Collections.sort(inputList, new Comparator() {

            public int compare(Object o1, Object o2) {
                 String s1 = (String)o1;
                 String s2 = (String)o2;

                 String integer1[] = s1.split("[^0-9]");
                 String integer2[] = s2.split("[^0-9]");
                 String chars1[] = s1.split("[0-9]+");
                 String chars2[] = s2.split("[0-9]+");

                 Integer i1 = new Integer( Integer.parseInt(integer1[0]) );
                 Integer i2 = new Integer( Integer.parseInt(integer2[0]) );

                 if (i1.equals(i2))
                    return chars1[1].compareTo(chars2[1]);
                  else
                     return i1.compareTo(i2);
            }
        });
         
        System.out.println("\nStrings sorted List ...");
        for(int i = 0; i < inputList.size(); i++)
            System.out.println((String)inputList.get(i));
    }
}

Hello zzynx,

         I really appreciate the response but I don't know, I already tried the code 2 days back without writing different function and different possibilities. But it doesn't work for me. The arguments which I passed are 115R 1125R 147C 37R 57R 37C and u seem to get the output as expected but I get different output which is different from what I want which is weird. The output which I got is :

Strings sorted List ...
1125R
115R
147C
37C
37R
57R

        Can you send me the code which u executed on ur side.

Thanks

So? You have found the problem?
Thanks for accepting

Hi zzynx,

      I have some problem with the code, I am getting an exception as below:

java.lang.ArrayIndexOutOfBoundsException: 0
      at SortObjects$1.compare(SortObjects.java:44)
      at java.util.Arrays.mergeSort(Arrays.java:1278)
      at java.util.Arrays.sort(Arrays.java:1219)
      at java.util.Collections.sort(Collections.java:155)
      at SortObjects.main(SortObjects.java:24)
Exception in thread "main"

and the code is as below:


import java.util.*;

public class SortObjects
{    
    public static void main(String s[])
    {
        String t[] = { "NITT", "A123" };  
       
        List inputList = new ArrayList(Arrays.asList(t));          
        //ArrayList inputList = new ArrayList(Arrays.asList(s));
       
        if(inputList != null && inputList.size() > 0)
        {
              Collections.sort(inputList, new Comparator()
              {
                  public int compare(Object o1, Object o2)
                  {
                       String s1 = (String)o1;
                       String s2 = (String)o2;
                      
                       String integer1[] = s1.split("[^0-9]");
                       String integer2[] = s2.split("[^0-9]");
      
                       String chars1[] = s1.split("[0-9]+");
                       String chars2[] = s2.split("[0-9]+");
      
                       Integer i1 = new Integer(Integer.parseInt(integer1[0]));
                                 Integer i2 = new Integer(Integer.parseInt(integer2[0]));
          
                       if (i1.equals(i2))
                          return chars1[1].compareTo(chars2[1]);
                        else
                           return i1.compareTo(i2);
                  }
              });
        }
         
        System.out.println("\nStrings sorted List ...");
        for(int i = 0; i < inputList.size(); i++)
            System.out.println((String)inputList.get(i));
    }
}

Please help me with this.

Thanks in advance.
Sunny

Well, the code I gave you was for sorting items of the following format: "<number><characters>"
Now, apparently want to sort items of these formats "<characters only>" and "<characters><number>".
The code should be adapted for that.

Hi zzynx, I am having some problem with this program. I tried so many ways for fixing this but no luck. I need help with this problem. Below is the code:

import java.util.*;

public class SortObjects
{
      public static ArrayList getSortedList(ArrayList sortableList)
      {
            if(sortableList != null)
            {
                  if(sortableList.size() == 0)
                        return sortableList;
            }
            else
                  return sortableList;
      
            List inputList = sortableList;
            Collections.sort(inputList, new Comparator()
            {
                  public int compare(Object o1, Object o2)
                  {
                        String s1 = (String)o1;
                        String s2 = (String)o2;
                        System.out.println("$$$$$$$$$s1 : "+s1+"   s2:"+s2);
      
                        String integer1[] = s1.split("[^0-9]");
                        String integer2[] = s2.split("[^0-9]");
                        String chars1[] = s1.split("[0-9]+");
                        String chars2[] = s2.split("[0-9]+");
      
                        Integer i1 = null;
                        Integer i2 = null;
                        String str1 = null;
                        String str2 = null;
      
                        if(integer1.length > 0 && integer2.length > 0)
                        {
                              try
                              {
                                    i1 = new Integer(Integer.parseInt(integer1[0]));
                                    i2 = new Integer(Integer.parseInt(integer2[0]));
                              }
                              catch(NumberFormatException e)
                              {
                                    if(chars1.length > 0 && chars2.length > 0)
                                    {
                                          str1 = chars1[0];
                                          str2 = chars2[0];
                                    }
                              }
                        }
                        else if(chars1.length > 0 && chars2.length > 0)
                        {
                              str1 = chars1[0];
                              str2 = chars2[0];
                        }
                        System.out.println("i1 :"+i1.intValue()+"   i2 :"+i2.intValue());
                        if(i1 != null && i2 != null)
                        {
                              System.out.println("%%%%%%%%");
                              if (i1.equals(i2))
                              {
                                    System.out.println("%%%%%%%%1111 chars1[1] :"+str1);
                                    System.out.println("%%%%%%%%%  chars2[1] :"+str2);
                                    if(chars1[1] != null && chars2[1] != null)
                                          return chars1[1].compareTo(chars2[1]);
                                    else
                                          return 0;
                              }
                              else
                              {      
                                    System.out.println("%%%%%%%%2222222222");
                                    return i1.compareTo(i2);
                              }
                        }
                        else if(str1 != null && str2 != null)
                        {      
                              if(str1.equals(str2))
                                    return chars1[1].compareTo(chars2[1]);
                              else
                                    return str1.compareTo(str2);
                        }
                        return 0;
                  }
            });
            return (ArrayList)inputList;
      }
      
      public static void main(String[] args)
      {
            SortObjects sTest  = new SortObjects();
            ArrayList list = new ArrayList();
            list.add("011");
            list.add("011A");
            list.add("011AB");
            list.add("011AA");
            ArrayList sList = getSortedList(list);
            for(int i=0; i < sList.size(); i++)
            {
                  System.out.println("i value :"+i+"    data :"+(String)sList.get(1));
            }
      }
}

Exception which I am getting is :

$$$$$$$$$s1 : 011   s2:011A
i1 :11   i2 :11
%%%%%%%%
%%%%%%%%1111 chars1[1] :null
%%%%%%%%%  chars2[1] :null
java.lang.ArrayIndexOutOfBoundsException: 1
      at SortObjects$1.compare(SortObjects.java:68)
      at java.util.Arrays.mergeSort(Arrays.java:1278)
      at java.util.Arrays.sort(Arrays.java:1219)
      at java.util.Collections.sort(Collections.java:155)
      at SortObjects.getSortedList(SortObjects.java:21)
      at SortObjects.main(SortObjects.java:100)
Exception in thread "main"

any help would be appreciated.

Thanks in advance

1) You should have posted another question concerning this
2) How do you want the given list to be sorted? What are the rules?

hey zzynx, thanks for responding but I was able to resolve that problem. Anyway, I appreciate it, Thanks