How to apply custom drop down style on custom spinner adapter?-CodePudding

I created custom spinner adapter class (source code bellow), because I needed to apply custom design for spinner (i.e. custom_spinner_item). That part is ok and everything shows as I intended.

CustomSpinnerAdapter.java

public class CustomSpinnerAdapter extends BaseAdapter {

    private Context context;
    private String[] cities;

    public CustomSpinnerAdapter(Context context, String[] cities) {
        this.context = context;
        this.cities = cities;
    }

    @Override
    public int getCount() {
        return cities != null ? cities.length : 0;
    }

    @Override
    public Object getItem(int i) {
        return i;
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        View rootView = LayoutInflater.from(context).inflate(R.layout.custom_spinner_item, viewGroup, false);

        TextView txtName = rootView.findViewById(R.id.customSpinnerItemTextView);
        txtName.setText(cities[i]);

        return rootView;
    }
}

custom_spinner_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">

    <TextView
        android:id="@ id/customSpinnerItemTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="City"
        android:layout_centerVertical="true"
        android:layout_marginStart="5dp"
        android:layout_marginEnd="22dp"
        android:textAppearance="@style/toolbar_text_white"/>

</LinearLayout>

Problems start to appear during styling of drop down view of spinner. Since my custom adapter class is NOT ArrayAdapter<CharSequence> derivative, I cannot apply setDropDownViewResource method on its objects, so I cannot easily apply XML description of drop down view like I did with custom_spinner_item. I need somehow to apply custom drop down view XML description on my custom adapter. Does someone have any idea how to achieve described? Thanks!

CodePudding user response：

You can override getDropDownView() in BaseAdapter to define a custom drop down item layout.

getDropDownView() can be built like getView(); preferably with a ViewHolder pattern (you should do that in getView() as well) to help in view recycling.