imin imin - 5 months ago 614
Android Question

CheckBox in RecyclerView keeps on checking different items

Here's the XML for my items inside the RecyclerView

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="@+id/cvItems"
android:layout_height="wrap_content"
android:layout_width="fill_parent"
android:layout_margin="2dp"
card_view:cardElevation="0dp"
card_view:contentPadding="0dp"
card_view:cardBackgroundColor="#FFFFFF"
>

<LinearLayout
android:orientation="horizontal"
android:layout_height="fill_parent"
android:layout_width="fill_parent">
<TextView
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="0.8"
android:id="@+id/tvContent"
android:textSize="15dp"
android:paddingLeft="5dp"
android:paddingRight="5dp" />
<CheckBox
android:id="@+id/cbSelect"
android:layout_width="0dip"
android:layout_weight="0.2"
android:layout_height="match_parent"
android:button="@drawable/cb_checked"
android:gravity="center_horizontal"
android:textAlignment="center"
android:layout_gravity="center_horizontal" />
</LinearLayout>
</android.support.v7.widget.CardView>


And here's the RecyclerView adapter that inflate the layout above for each of its items:

public class AdapterTrashIncome extends RecyclerView.Adapter<AdapterTrashIncome.ViewHolder> {

private ArrayList<ObjectIncome> myItems = new ArrayList<>();

public AdapterTrashIncome(ArrayList<ObjectIncome> getItems, Context context){
try {
mContext = context;
myItems = getItems;
}catch (Exception e){
Log.e(FILE_NAME, "51: " + e.toString());
e.printStackTrace();
}
}

public class ViewHolder extends RecyclerView.ViewHolder {
public TextView tvContent;
public CheckBox cbSelect;

public ViewHolder(View v) {
super(v);
tvContent = (TextView) v.findViewById(R.id.tvContent);
cbSelect = (CheckBox) v.findViewById(R.id.cbSelect);
}
}

@Override
public void onBindViewHolder(ViewHolder holder, final int position) {
final ObjectIncome objIncome = myItems.get(position);
String content = "<b>lalalla</b>";
holder.tvContent.setText(Html.fromHtml(content));
}
}


The problem is, let's say I have 10 items inside the RecyclerView. When I checked the checkbox on item 1,2,3 then I scroll down the RecyclerView, suddenly some of the other items eg items 8,9 is checked. And when I scroll up again, item 1 and 3 is checked but not item 2. Any idea why this happen?

Answer

It's normal. You are not setting your checkbox selected or not. You are selecting one and View holder keeps it selected. You can add a bolean variable into your ObjectIncome object and keep your item's selection status.

You may look at my example. You can do something like that:

public class AdapterTrashIncome extends RecyclerView.Adapter<AdapterTrashIncome.ViewHolder> {

    private ArrayList<ObjectIncome> myItems = new ArrayList<>();

    public AdapterTrashIncome(ArrayList<ObjectIncome> getItems, Context context){
        try {
            mContext = context;
            myItems = getItems;
            }catch (Exception e){
            Log.e(FILE_NAME, "51: " + e.toString());
            e.printStackTrace();
        }
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView tvContent;
        public CheckBox cbSelect;

        public ViewHolder(View v) {
            super(v);
            tvContent = (TextView) v.findViewById(R.id.tvContent);
            cbSelect = (CheckBox) v.findViewById(R.id.cbSelect);
        }
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, final int position) {
        final ObjectIncome objIncome = myItems.get(position);
        String content = "<b>lalalla</b>";
        holder.tvContent.setText(Html.fromHtml(content));

        //in some cases, it will prevent unwanted situations
        holder.cbSelect.setOnCheckedChangeListener(null);

        //if true, your checkbox will be selected, else unselected
        holder.cbSelect.setChecked(objIncome.isSelected());

        holder.cbSelect.setOnCheckedChangeListener(new OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    //set your object's last status
                    objIncome.setSelected(isChecked);
            }
        });

    }
}