Android: Custom ArrayAdapter(s) for different custom objects

Question

I have a number of custom objects that are significantly different from each other. These objects are stored in different lists and are to be displayed in different ListViews. Because of the design of these ListViews, I need to create my own custom ArrayAdapter. The thing is, the ListView design is supposed to be the same for all ListViews regardless of the objects in the list.

To accomplish this I created an ArrayAdapter for every type of object. E.g. for a custom object coA I made an ArrayAdapter coAAdapter, and for custom object coB I made an ArrayAdapter coBAdapter. This seems very unnecessary to me, since there are next to no difference between these adapters except what kind of ArrayAdapter the custom adapters extends and their constructors:

Adapter for class CoA:

public class CoAAdapter extends ArrayAdapter<CoA> {
     public CoAAdapter (Context context, int resource, List<CoA> objects) {...}
}

Adapter for class CoB:

public class CoBAdapter extends ArrayAdapter<CoB> {
     public CoBAdapter (Context context, int resource, List<CoB> objects) {...}
}

Is this how custom ArrayAdapters are supposed to be used, or is there a way to make this design a lot simpler, like having one custom ArrayAdapter for all custom objects?

I have thought about some different solutions, like creating a generic custom adapter or using inheritance by creating a common base class for my custom objects, but after some research none of these seems like a good approach.

Make one interface that suit to all Your Objects and can draw all needed data. Then You can write adapter for that interface — Gooziec
– Gooziec, Commented Dec 16, 2013 at 9:45
@Apoorv Yes, more or less. I have a couple of layouts for my list items which differs only in the text color, but otherwise they are identical. — HigiPha
– HigiPha, Commented Dec 16, 2013 at 9:49
@Gooziec Just to clarify, I should create a common interface and let all of my other classes extend it? At least that's what I've tried to do, but it doesn't work: the array adapter does not accept the child classes. — HigiPha
– HigiPha, Commented Dec 16, 2013 at 10:20

Salil · Accepted Answer · 2013-12-17 03:38:23Z

3

You can define your adapter like this:

 public class MyArrayAdapter<T> extends ArrayAdapter<T> 
 {
      HashMap<T, Integer> mIdMap = new HashMap<T, Integer>();

      public MyArrayAdapter(Context context, int textViewResourceId, List<T> objects) {
        super(context, textViewResourceId, objects);
        for (int i = 0; i < objects.size(); ++i) {
          mIdMap.put(objects.get(i), i);
        }
      }
  }

answered Dec 17, 2013 at 3:38

Salil

9,7529 gold badges45 silver badges59 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

HigiPha Over a year ago

This approach crossed my mind, but I read that this is not an all to great solution due to not being type safe?

Salil Over a year ago

It is type-safe. Why do you think it is not?

HigiPha Over a year ago

Sorry, I read about it in some similar questions and I misinterpreted one of the answers. I'll try it then!

Gerry Over a year ago

That's cool but there is more. Now my spinner is displaying a list of object references, will begin the search for the method to override......

Abhishek Shukla · Accepted Answer · 2013-12-16 09:45:17Z

0

Probably, you want to use a BaseAdapter. And in the getView() of that adapter, check for the instanceof of the object, do things accordingly.

answered Dec 16, 2013 at 9:45

Abhishek Shukla

1,2428 silver badges11 bronze badges

Comments

Gooziec · Accepted Answer · 2013-12-16 10:26:18Z

0

public interace SomeInterface
{
    public String getString();
}

public class classA implements SomeInterface
{
    ...

    @Override
    public String getString()
    {
        return "blabla";
    }
}

public class classB implements SomeInterface
{
    ...

    @Override
    public String getString()
    {
        return "whatever";
    }
}

public class InterfaceAdapter extends ArrayAdapter<SomeInterface> 
{
     public InterfaceAdapter (Context context, int resource, List<SomeInterface> objects) {...}
}

answered Dec 16, 2013 at 10:26

Gooziec

2,7761 gold badge15 silver badges18 bronze badges

Collectives™ on Stack Overflow

Android: Custom ArrayAdapter(s) for different custom objects

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related