I am trying to add an EditText field with autocomplete functionality
(in the form of a dropdown with a list of options that can be selected as the user types into the input box) to a popup dialog.
However, rather than simply have the autocomplete suggest options based on the input text,
I need to be able to control what is suggested on each key press, and update any adaptor options accordingly.

I have tried to use two separate widgets: android.widget.AutoCompleteTextView, and “AutoCompleteDropDown” an extenstion of androidx.appcompat.widget.AppCompatAutoCompleteTextView
obtained from another thread (which I will attempt to link here if I can find it again)

My dialog code is as follows:

private static class CreateDialog {

    final private AlertDialog createDialog;

    public CreateDialog(Activity activity){
        AlertDialog.Builder alertDialog = new AlertDialog.Builder(activity);
        alertDialog.setIcon(R.drawable.ic_baseline_search_24);
        alertDialog.setTitle("Search");

        //Initialise layout for dialog
        LinearLayout layout = new LinearLayout(activity);
        layout.setOrientation(LinearLayout.VERTICAL);

        //Search selection
        TextView label = new TextView(activity);
        label.setText("Selection");
        layout.addView(label);

        //AutoCompleteDropDown value = new AutoCompleteDropDown(activity);
        AutoCompleteTextView value = new AutoCompleteTextView(activity);
        ArrayAdapter<String> adaptor = new ArrayAdapter(activity, android.R.layout.simple_dropdown_item_1line, new String[]{"A", "AAA", "AAAAA"});
        value.setAdapter(adaptor);
        layout.addView(value);

        //Construct dialog and add button functionality
        alertDialog.setView(layout);
        alertDialog.setPositiveButton("Save", (dialog, which) -> dialog.dismiss());
        alertDialog.setNegativeButton("Cancel", (dialog, which) -> dialog.dismiss());
        createDialog = alertDialog.create();
    }

    public void show(){
        createDialog.show();
    }

    public void onSubmit(){}
}

(AutoCompleteTextView is enabled here on line 20)

With this enabled, the autocomplete widget will only display options which are a case insensitive extension to what is already typed:

I’m not sure if it’s possible to override this.

The code for AutoCompleteDropDown is as follows:

public class AutoCompleteDropDown extends AppCompatAutoCompleteTextView {
    //    implements AdapterView.OnItemClickListener
    private static final int MAX_CLICK_DURATION = 200;
    private long startClickTime;
    private boolean isPopup;
    private int mPosition = ListView.INVALID_POSITION;

    public AutoCompleteDropDown(Context context) {
        super(context);
//        setOnItemClickListener(this);
    }

    public AutoCompleteDropDown(Context arg0, AttributeSet arg1) {
        super(arg0, arg1);
//        setOnItemClickListener(this);
    }

    public AutoCompleteDropDown(Context arg0, AttributeSet arg1, int arg2) {
        super(arg0, arg1, arg2);
//        setOnItemClickListener(this);
    }

    @Override
    public boolean enoughToFilter() {
        return true;
    }

    @Override
    protected void onFocusChanged(boolean focused, int direction,
                                  Rect previouslyFocusedRect) {
        super.onFocusChanged(focused, direction, previouslyFocusedRect);
        if (focused) {
            if(this.getText().length()>0 && this.getAdapter() !=null) { performFiltering("", 0); }
            InputMethodManager imm = (InputMethodManager) getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
            imm.hideSoftInputFromWindow(getWindowToken(), 0);
            setKeyListener(null);
            dismissDropDown();
        } else {
            isPopup = false;
        }
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {

        switch (event.getAction()) {
            case MotionEvent.ACTION_UP: {
                if (isPopup) {
                    dismissDropDown();
                } else {
                    requestFocus();
                    showDropDown();
                }
                break;
            }
        }

        return super.onTouchEvent(event);
    }

    @Override
    public void showDropDown() {
        super.showDropDown();
        isPopup = true;
    }

    @Override
    public void dismissDropDown() {
        super.dismissDropDown();
        isPopup = false;
    }
    
    @Override
    public void setCompoundDrawablesWithIntrinsicBounds(Drawable left, Drawable top, Drawable right, Drawable bottom) {
        Drawable dropdownIcon = ContextCompat.getDrawable(getContext(), R.drawable.ic_baseline_keyboard_arrow_down_24);
        if (dropdownIcon != null) {
            right = dropdownIcon;
            right.mutate().setAlpha(66);
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            super.setCompoundDrawablesRelativeWithIntrinsicBounds(left, top, right, bottom);
        } else {
            super.setCompoundDrawablesWithIntrinsicBounds(left, top, right, bottom);
        }

    }
    
    public int getPosition() {
        return mPosition;
    }
}

With this enabled, I can toggle the expansion of the dropdown and have it display all items in the adaptor (which I can dynamically update).
However, typing into the input field is having no effect and nothing is displayed (unless a dropdown option is selected, in which case it will display fine)

Is there a way to achieve my requirements of controlling which autocomplete options are presented on each key press, and still have what the user types be displayed?