I've come to a problem with the Android GridView. I already tried various solutions from Stackoverflow but none of them actually worked.
I'm populating a GridView with the help of an ArrayAdapter. The Adapter inflates a layout containing only an image and a checkbox. I'm using that "convertView"-thing in order to prevent flickering when the images get added (nearly 500 images are getting added to the GridView).
The Problem: When I check a checkbox and scroll, the checked-state disappears. Also, when I for instance check multiple GridView item's checkboxes, the pattern of selection endlessly continues for all the following elements.
My GridView is the child-element of a RelativeLayout. The RelativeLayout is used as the root element of a fragment being used in a ViewPager:
<GridView
android:id="@+id/MainGrid"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/appBackgroundColor"
android:drawSelectorOnTop="false"
android:listSelector="#00000000"
android:numColumns="2"
android:paddingLeft="6dp"
android:paddingTop="5dp"
android:paddingRight="6dp"
android:translationZ="2dp" />
I'm populating the GridView with the help of a thread, which is downloading image-data from a website. I think there shouldn't be a problem with this, but for completeness, here is the code:
//Declaring the Array
ArrayList<GridImage> ImageArray = new ArrayList<>();
//And the adapter
Adapter_GridAdapter GridViewAdapter = new Adapter_GridAdapter (getActivity().getApplicationContext(), ImageArray );
//The following is executed 500 times in a thread
ImageArray.add(new GridImage(URL));
getActivity().runOnUiThread(new Runnable() {
@Override
public void run() {
GridViewAdapter.notifyDataSetChanged();
}
});
The code of the GridView adapter:
public class Adapter_GridAdapter extends ArrayAdapter<GridImage> {
Context context;
public Adapter_GridAdapter (Context context, ArrayList<GridImage> SearchResults) {
super(context, 0, SearchResults);
this.context = context;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = LayoutInflater.from(getContext());
View view = convertView;
if (convertView == null) {
view = inflater.inflate(R.layout.griditem_ig_post, null);
final ImageView ThisViewIMG = view.findViewById(R.id.GridImageView);
//Calculating Image Height (Square Image)
ThisViewIMG.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
@Override
public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
ThisViewIMG.removeOnLayoutChangeListener(this);
ThisViewIMG.getLayoutParams().height = ThisViewIMG.getWidth();
ThisViewIMG.requestLayout();
}
});
}
final GridImage ThisImg = getItem(position);
final ImageView ThumbnailImage = view.findViewById(R.id.GridImageView);
//THIS IS THE CUSTOM CHECKBOX!
final CustomCheckBox scb = (CustomCheckBox) view.findViewById(R.id.MyCheckBox);
//I AM SAVING THE VALUE IN THE OBJECT (TRY #38181 THAT DIDN'T WORK)
scb.setChecked(ThisImg.IsChecked);
scb.setOnCheckedChangeListener(new CustomCheckBox.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CustomCheckBox checkBox, boolean isChecked) {
Log.d("CustomCheckBox", String.valueOf(isChecked));
ThisImg.setChecked(isChecked);
}
});
Glide.with(context).load(Post.IMG_ThumbnailURL).fitCenter().into(ThumbnailImage);
return view;
}
}
The Object itself is quite simple, the problem (i think) also shouldn't hide in here:
public class GridImage{
public String PostURL;
public Boolean IsChecked = false;
GridImage(String URL){
PostURL = URL;
}
public void setChecked(Boolean checked) {
IsChecked = checked;
}
}
What I already tried:
When doing with ListView/GridView adapters, I always avoid to have final and onCheckedChangeListener because both may have problem sometimes even the logic seems right, so try the code below:
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = LayoutInflater.from(getContext());
View view = convertView;
if (convertView == null) {
view = inflater.inflate(R.layout.griditem_ig_post, null);
ImageView ThisViewIMG = view.findViewById(R.id.GridImageView);
//Calculating Image Height (Square Image)
ThisViewIMG.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
@Override
public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
v.removeOnLayoutChangeListener(this);
v.getLayoutParams().height = v.getWidth();
v.requestLayout();
}
});
}
GridImage ThisImg = getItem(position);
ImageView ThumbnailImage = view.findViewById(R.id.GridImageView);
//THIS IS THE CUSTOM CHECKBOX!
CustomCheckBox scb = (CustomCheckBox) view.findViewById(R.id.MyCheckBox);
scb.setChecked(ThisImg.IsChecked);
scb.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
CustomCheckBox cb = (CustomCheckBox)view;
int position = (int)cb.getTag();
GridImage ThisImg = getItem(position);
Log.d("CustomCheckBox", String.valueOf(!ThisImg.IsChecked));
ThisImg.setChecked(!ThisImg.IsChecked);
cb.setChecked(ThisImg.IsChecked);
}
});
Glide.with(context).load(Post.IMG_ThumbnailURL).fitCenter().into(ThumbnailImage);
scb.setTag(position);
return view;
}
Hope that helps!