ComboBox is a very useful widget that allows user to type the text in or select from predefined list of options.

While Android comes with Spinner, it is not always what we need. Spinner is a Listbox that only lets user to chose from predefined options.

It is fairly easy to create "sort of" ComboBox however. Here is how:

package myWidgets;

import android.content.Context;
import android.database.Cursor;
import android.text.InputType;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AutoCompleteTextView;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.SimpleCursorAdapter;

public class ComboBox extends LinearLayout {

   private AutoCompleteTextView _text;
   private ImageButton _button;

   public ComboBox(Context context) {
       super(context);
       this.createChildControls(context);
   }

   public ComboBox(Context context, AttributeSet attrs) {
       super(context, attrs);
       this.createChildControls(context);
   }

   private void createChildControls(Context context) {
       this.setOrientation(HORIZONTAL);
       this.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
                       LayoutParams.WRAP_CONTENT));

       _text = new AutoCompleteTextView(context);
       _text.setSingleLine();
       _text.setInputType(InputType.TYPE_CLASS_TEXT
                       | InputType.TYPE_TEXT_VARIATION_NORMAL
                       | InputType.TYPE_TEXT_FLAG_CAP_SENTENCES
                       | InputType.TYPE_TEXT_FLAG_AUTO_COMPLETE
                       | InputType.TYPE_TEXT_FLAG_AUTO_CORRECT);
       _text.setRawInputType(InputType.TYPE_TEXT_VARIATION_PASSWORD);
       this.addView(_text, new LayoutParams(LayoutParams.WRAP_CONTENT,
                       LayoutParams.WRAP_CONTENT, 1));

       _button = new ImageButton(context);
       _button.setImageResource(android.R.drawable.arrow_down_float);
       _button.setOnClickListener(new OnClickListener() {
               @Override
               public void onClick(View v) {
                       _text.showDropDown();
               }
       });
       this.addView(_button, new LayoutParams(LayoutParams.WRAP_CONTENT,
                       LayoutParams.WRAP_CONTENT));
   }

   /**
    * Sets the source for DDLB suggestions.
    * Cursor MUST be managed by supplier!!
    * @param source Source of suggestions.
    * @param column Which column from source to show.
    */
   public void setSuggestionSource(Cursor source, String column) {
       String[] from = new String[] { column };
       int[] to = new int[] { android.R.id.text1 };
       SimpleCursorAdapter cursorAdapter = new SimpleCursorAdapter(this.getContext(),
                       android.R.layout.simple_dropdown_item_1line, source, from, to);
       // this is to ensure that when suggestion is selected
       // it provides the value to the textbox
       cursorAdapter.setStringConversionColumn(source.getColumnIndex(column));
       _text.setAdapter(cursorAdapter);
   }

   /**
    * Gets the text in the combo box.
    *
    * @return Text.
    */
   public String getText() {
       return _text.getText().toString();
   }

   /**
    * Sets the text in combo box.
    */
   public void setText(String text) {
       _text.setText(text);
   }
}