Set Background in GridView by item position

Question

I want to change the background color for specific item in GridView (by position).

gridview.getChildAt(1).setBackgroundResource(android.R.drawable.btn_default);

doesn't work.

If I use it in OnClickListener it works:

public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
    view.setBackgroundResource(android.R.drawable.btn_default);
}

but I want to change it without a click.

---

EDIT

ImageAdapter:

public class ImageAdapter extends BaseAdapter {
private final String TAG = getClass().toString();

private Context mContext;

public ImageAdapter(Context c) {
    mContext = c;
}

public int getCount() {
    return mThumbIds.length;
}

public Object getItem(int position) {
    return null;
}

public long getItemId(int position) {
    return 0;
}

public View getView(int position, View convertView, ViewGroup parent) {
    ImageView imageView;
    if (convertView == null) {  // if it's not recycled, initialize some attributes
        imageView = new ImageView(mContext);
        imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setPadding(8, 8, 8, 8);
    } else {
        imageView = (ImageView) convertView;
    }

    parent.getChildAt(1).setBackgroundColor(Color.RED);

    imageView.setImageResource(mThumbIds[position]);
    return imageView;
}

Activity:

final GridView gridview = (GridView) view.findViewById(R.id.gridView);
gridview.setAdapter(new ImageAdapter(MainActivity.this));
gridview.setSelection(0);
    gridview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    View previous = null;
    @Override
    public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            if(previous == view) {
                view.setBackgroundResource(android.R.drawable.btn_default);
            } else {
                view.setBackgroundResource(android.R.drawable.btn_default);
                if(previous != null) previous.setBackgroundResource(0);
                previous =  view;
            }

        }
    });

XML:

<GridView
    android:id="@+id/gridView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:numColumns="4" >
</GridView>

Solution 1

Use this in your getView()and see if your Background changes:

gridView.getChildAt(position).setBackgroundColor(Color.RED);

Don't forget to use @Override on getView():

@Override
public View getView(int position, View convertView, ViewGroup parent) {

}

Solution 2

Try this

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;
        if (convertView == null) {  // if it's not recycled, initialize some attributes
            imageView = new ImageView(mContext);
            imageView.setLayoutParams(new GridView.LayoutParams(85, 85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);
        } else {
            imageView = (ImageView) convertView;
        }


        if(position==1)
             imageview.setBackgroundColor(Color.RED);

        imageView.setImageResource(mThumbIds[position]);
        return imageView;
    }

Solution 3

You can use setBackground for Item Adapter.

Try this. item_image.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/bg_item_selection">

    <ImageView
        android:layout_width="200dp"
        android:layout_height="200dp" />
</LinearLayout>

bg_item_selection.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">

<item android:drawable="@color/white_color" android:state_pressed="false"/>
<item android:drawable="@color/black"/>

In Adapter.

 @Override
public View getView(final int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    ItemUserEntity itemUserEntity = new ItemUserEntity();
    itemUserEntity = arrayList.get(position);
    LayoutInflater inflater = (LayoutInflater) mContext
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    if (convertView == null) {

        convertView = inflater.inflate(R.layout.item_image, parent,
                false);
    }


    return convertView;

}

Comments

[Dennis]

The parent in getView() is the gridView?

[Dennis]

GridView gridview = (GridView) parent.findViewById(R.id.gridView); gridview.getChildAt(0).setBackgroundResource(android.R.drawa‌​ble.btn_default); and parent..getChildAt(0).setBackgroundResource(android.R.drawab‌​le.btn_default); doesn't work.

[sebster]

in your case yes, it's the GridView

[Dennis]

parent.getChildAt(1).setBackgroundResource(android.R.drawabl‌​e.btn_default); doesn't work =\

[sebster]

try it with .setBackgroundColor(Color.RED); and see if it changes color

[sebster]

edit your question and post your entire code for the class where you use the GridView

[sebster]

are you using a selector in your drawable resources?.. also post the related XML files

[sebster]

Also try not to use android.R.drawable.btn_default. Instead create a selector inside your drawable resource folder and use that one to set states.

[Dennis]

I posted the adapter, activity and the xml file. Maybe it's important - my grid view is in a custom dialog. Thank you for your help!