Show ListView As Dropdown In Android

MainActivity.java – show the button, set the items for the dropdown list, create the pop up window and then show it as dropdown when the button was touched. 

package com.example.showasdropdownexample;

import java.util.ArrayList;
import java.util.List;

import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.PopupWindow;
import android.widget.TextView;
import android.app.Activity;
import android.graphics.Color;

public class MainActivity extends Activity {

    String TAG = "MainActivity.java";

    String popUpContents[];
    PopupWindow popupWindowDogs;
    Button buttonShowDropDown;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // initialize pop up window items list

        // add items on the array dynamically
        // format is DogName::DogID
        List<String> dogsList = new ArrayList<String>();
        dogsList.add("Akita Inu::1");
        dogsList.add("Alaskan Klee Kai::2");
        dogsList.add("Papillon::3");
        dogsList.add("Tibetan Spaniel::4");

        // convert to simple array
        popUpContents = new String[dogsList.size()];
        dogsList.toArray(popUpContents);


        // initialize pop up window
        popupWindowDogs = popupWindowDogs();


        // button on click listener

        View.OnClickListener handler = new View.OnClickListener() {
            public void onClick(View v) {

                switch (v.getId()) {

                case R.id.buttonShowDropDown:
                    // show the list view as dropdown
                    popupWindowDogs.showAsDropDown(v, -5, 0);
                    break;
                }
            }
        };

        // our button
        buttonShowDropDown = (Button) findViewById(R.id.buttonShowDropDown);
        buttonShowDropDown.setOnClickListener(handler);
    }

    public PopupWindow popupWindowDogs() {

        // initialize a pop up window type
        PopupWindow popupWindow = new PopupWindow(this);

        // the drop down list is a list view
        ListView listViewDogs = new ListView(this);

        // set our adapter and pass our pop up window contents
        listViewDogs.setAdapter(dogsAdapter(popUpContents));

        // set the item click listener
        listViewDogs.setOnItemClickListener(new DogsDropdownOnItemClickListener());

        // some other visual settings
        popupWindow.setFocusable(true);
        popupWindow.setWidth(250);
        popupWindow.setHeight(WindowManager.LayoutParams.WRAP_CONTENT);

        // set the list view as pop up window content
        popupWindow.setContentView(listViewDogs);

        return popupWindow;
    }

    /*
     * adapter where the list values will be set
     */
    private ArrayAdapter<String> dogsAdapter(String dogsArray[]) {

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, dogsArray) {

            @Override
            public View getView(int position, View convertView, ViewGroup parent) {

                // setting the ID and text for every items in the list
                String item = getItem(position);
                String[] itemArr = item.split("::");
                String text = itemArr[0];
                String id = itemArr[1];

                // visual settings for the list item
                TextView listItem = new TextView(MainActivity.this);

                listItem.setText(text);
                listItem.setTag(id);
                listItem.setTextSize(22);
                listItem.setPadding(10, 10, 10, 10);
                listItem.setTextColor(Color.WHITE);

                return listItem;
            }
        };

        return adapter;
    }
}

DogsDropdownOnItemClickListener.java – triggered when an item on the dropdown list was touched, it will change the text on the button and show a toast with the ID of the selected item.  

package com.example.showasdropdownexample;

import android.content.Context;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.Toast;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.TextView;

public class DogsDropdownOnItemClickListener implements OnItemClickListener {

    String TAG = "DogsDropdownOnItemClickListener.java";

    @Override
    public void onItemClick(AdapterView<?> arg0, View v, int arg2, long arg3) {

        // get the context and main activity to access variables
        Context mContext = v.getContext();
        MainActivity mainActivity = ((MainActivity) mContext);

        // add some animation when a list item was clicked
        Animation fadeInAnimation = AnimationUtils.loadAnimation(v.getContext(), android.R.anim.fade_in);
        fadeInAnimation.setDuration(10);
        v.startAnimation(fadeInAnimation);

        // dismiss the pop up
        mainActivity.popupWindowDogs.dismiss();

        // get the text and set it as the button text
        String selectedItemText = ((TextView) v).getText().toString();
        mainActivity.buttonShowDropDown.setText(selectedItemText);

        // get the id
        String selectedItemTag = ((TextView) v).getTag().toString();
        Toast.makeText(mContext, "Dog ID is: " + selectedItemTag, Toast.LENGTH_SHORT).show();

    }

}

activity_main.xml – Here is the XML layout file we used for the user interface of our example.  

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <Button
        android:id="@+id/buttonShowDropDown"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="Select your dog..." />

</RelativeLayout>