Android data binding with custom adapter

Question

I'm trying to use Android's Data Binding features with a custom adapter and a ListView. I'm having trouble overriding the custom adapter's getView method:

public class ChecksAdapter extends ArrayAdapter<Check> {

    public ChecksAdapter(Context context, ObservableList<Check> checks) {
        super(context, R.layout.check, checks);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        CheckBinding binding = DataBindingUtil.inflate(
                LayoutInflater.from(getContext()),
                R.layout.check, parent, false);
        binding.setCheck(this.getItem(position));

        // Return what?
    }
    
}

So my questions are:

Where do I get the View element that I should be returning? Or in other words, how can I bind the object to an inflated/converted view?
How can I reuse convertView when using data binding?
Is this the correct way to implement this? The guide is not very clear on ListViews

Here's the only reference of ListViews in the guide:

If you are using data binding items inside a ListView or RecyclerView adapter, you may prefer to use:
   ListItemBinding binding = ListItemBinding.inflate(layoutInflater, viewGroup, false);
   //or
   ListItemBinding binding = DataBindingUtil.inflate(layoutInflater, R.layout.list_item, viewGroup, false);

sergi · Accepted Answer · 2017-05-09 12:26:08Z

28

You should do the following for smooth scrolling though..

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    CheckBinding binding;
    if(convertView == null) {
        binding = DataBindingUtil.inflate(
                LayoutInflater.from(getContext()),
                R.layout.check, parent, false);
        convertView = binding.getRoot();
    }
    else {
        binding = (CheckBinding) convertView.getTag();
    }

    binding.setCheck(this.getItem(position));
    convertView.setTag(binding);
    return convertView;
}

edited May 9, 2017 at 12:26

answered Mar 23, 2016 at 10:11

sergi

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3 Comments

Aman Singhal Over a year ago

i don't know why but this is not working for me when i am using a cursor adapter

Thalatta Over a year ago

@sergi why are you checking if the convertView is null?

sergi Over a year ago

@Thalatta the first time that row is displayed the convertView.getTag() will return a null object because it has never been initialized. The code in the if branch will only be executed as initialization the first time the visible rows are displayed. As you scroll, the else branch will be reached.

csenga · Accepted Answer · 2016-08-25 07:52:38Z

11

According to this, you should return binding.getRoot().

View getRoot ()

Returns the outermost View in the layout file associated with the Binding. If this binding is for a merge layout file, this will return the first root in the merge tag.

edited Aug 25, 2016 at 7:52

answered Nov 26, 2015 at 17:23

csenga

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Comments

Calin · Accepted Answer · 2017-11-24 13:46:47Z

5

For completes here is the kotlin variant:

    val binding = convertView?.tag as? CheckBinding ?: CheckBinding.inflate(layoutInflater, parent, false)
    binding.check = this.getItem(position)
    binding.root.tag = binding

    return binding.root

answered Nov 24, 2017 at 13:46

Calin

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Comments

Khemraj Sharma · Accepted Answer · 2019-04-24 11:54:36Z

2

Recommended way

Use generated Binding class instead of DataBindingUtil class. See Documentation.

If you are using data binding items inside a Fragment, ListView, or RecyclerView adapter, you may prefer to use the inflate() methods of the bindings classes

Use

binding = CheckBinding.inflate(this, parent, false);

instead of

binding = DataBindingUtil.inflate(
                LayoutInflater.from(getContext()),
                R.layout.check, parent, false);

Other code will be same as @sergi

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    CheckBinding binding;
    if(convertView == null) {
        binding = CheckBinding.inflate(this, parent, false);
        convertView = binding.getRoot();
    }
    else {
        binding = (CheckBinding) convertView.getTag();
    }

    binding.setCheck(this.getItem(position));
    convertView.setTag(binding);
    return convertView;
}

edited Apr 24, 2019 at 11:54

answered Aug 7, 2018 at 6:08

Khemraj Sharma

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1 Comment

Entreco Over a year ago

When I use this approach, I often get lint warnings indicating R.layout.check appears to be unused. Hence, I prefer to use DataBindingUtil

hering · Accepted Answer · 2017-03-15 14:44:18Z

1

ItemTickFilterBinding mFilterBinding;

    if (convertView==null) {
        mFilterBinding= DataBindingUtil.inflate(
                LayoutInflater.from(mContext),
                R.layout.item_tick_filter, parent, false);
        convertView.setTag(mFilterBinding);
    }
    else {
        mFilterBinding=(ItemTickFilterBinding)convertView.getTag();
    }

edited Mar 15, 2017 at 14:44

hering

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answered Mar 15, 2017 at 12:05

smith kashyap

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1 Comment

smith kashyap Over a year ago

in base adapter's method getView .mFilterBinding is the instance of listrow layout and u should set tag on convert view and get in else part also.

Yessy · Accepted Answer · 2020-11-11 06:23:04Z

DataBindingUtil will save the ViewDataBinding object to view.tag, so you can retrieve it later by DataBindingUtil.getBinding(convertView)

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    return getViewForResource(mResourceId, position, convertView, parent);
}

@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
    return getViewForResource(mDropDownResourceId, position, convertView, parent);
}

public View getViewForResource(int resourceId, int position, View convertView, ViewGroup parent) {
    final ViewDataBinding binding = (convertView != null) ? DataBindingUtil.getBinding(convertView) : DataBindingUtil.inflate(mLayoutInflater, resourceId, parent, false);
    binding.setVariable(BR.viewModel, getItem(position));
    return binding.getRoot();
}

Mudit Goel · Accepted Answer · 2023-06-26 05:03:59Z

-1

For GridView adapters or custom adapter following code worked for me :

override fun getView(position: Int, convertView: View?, container: ViewGroup?): View {
    val binding = convertView?.tag as? MenuItemBinding ?:
    MenuItemBinding.inflate(LayoutInflater.from(ctx), container, false)

    val menuItem = menuList[position]
    binding.txtVw.text = menuItem.title
    binding.imgVwIcon.setImageResource(menuItem.iconId)
    return binding.root
}

MenuItemBinding is on the basis of the name of the layout file here the layout file name is 'menu_item.xml'.

edited Jun 26, 2023 at 5:03

answered Jun 25, 2023 at 14:45

Mudit Goel

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