如何在列表视图中对手机联系人进行排序？

Question

I have created a listview based on this tutorial:

http://www.vogella.com/articles/AndroidListView/article.html

In that link, I've implemented

13> Selecting multiple items in the ListView

My list view is working correctly. I've customized the list view by populating it with phone contacts using the following code:

private List<Model> getModel()        
{                  
    List<Model> list = new ArrayList<Model>();    
    ContentResolver cr = getContentResolver();
    Cursor cur = cr.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null);
    if (cur.getCount() > 0)
    {
         while (cur.moveToNext())
         {
              String id = cur.getString(cur.getColumnIndex(ContactsContract.Contacts._ID));
              String name = cur.getString(cur.getColumnIndex(ContactsContract.Contacts.DISPLAY_NAME));
               if (Integer.parseInt(cur.getString(cur.getColumnIndex(ContactsContract.Contacts.HAS_PHONE_NUMBER))) > 0)
               {
                    // This inner cursor is for contacts that have multiple numbers.
                    Cursor pCur = cr.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " = ?", new String[] { id }, null);
                    while (pCur.moveToNext())
                    {
                         list.add(get(name));
                    }
                    pCur.close();
               }
         }
    }
    cur.close();
    return list;
}

Now the name of the contacts are getting displayed, but they are not sorted. How do I sort this?

Kindly help! Thanks in advance!

Answer 1

Let's look at this declaration.

List<Model> list = new ArrayList<Model>();    

This is an ArrayList object, paramaterized to type Model . Now , in the Model class that you have created, you can simply use the Comparable interface. To do this you add:

implements Comparable<Model>

to the end of your Model class header.

Then you will be forced to add an implementation for a method called compareTo . This is simply how you're comparing things.

When you have added this implementation, you can call Collections.sort() , and pass it the ArrayList object, list. This will sort the list for you.

So, the first thing to do is go to your Model class, which at the moment has a header that looks like this:

public class Model

What you want to do, is change it to this:

public class Model implements Comparable<Model>

Well this means that you have agreed to provide code for the Comparable interface. You now need to write a method, compareTo , in your Model class. Something like:

@Override
public int compareTo(Object arg0) {
   // At this point, you put your comparison code in.
}

If you wanted to sort them alphabetically, you can use the compareTo method that exists in a String object. You first, need to turn arg0 into a String object that you can work with:

String otherName = ((Member)arg0).getName();

Then you can simply return the value of the String compareTo method:

return otherName.compareTo(this.name);

Answer 2

Add Collections.sort(list) before return list. And check if the class Model implements Comparable. If not, you can use Collections.sort(list,comparator)