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.
  1. package com.example.showasdropdownexample;
  3. import java.util.ArrayList;
  4. import java.util.List;
  6. import android.os.Bundle;
  7. import android.view.View;
  8. import android.view.ViewGroup;
  9. import android.view.WindowManager;
  10. import android.widget.ArrayAdapter;
  11. import android.widget.Button;
  12. import android.widget.ListView;
  13. import android.widget.PopupWindow;
  14. import android.widget.TextView;
  15. import android.app.Activity;
  16. import android.graphics.Color;
  18. public class MainActivity extends Activity {
  20. String TAG = "MainActivity.java";
  22. String popUpContents[];
  23. PopupWindow popupWindowDogs;
  24. Button buttonShowDropDown;
  26. @Override
  27. protected void onCreate(Bundle savedInstanceState) {
  29. super.onCreate(savedInstanceState);
  30. setContentView(R.layout.activity_main);
  32. // initialize pop up window items list
  34. // add items on the array dynamically
  35. // format is DogName::DogID
  36. List<String> dogsList = new ArrayList<String>();
  37. dogsList.add("Akita Inu::1");
  38. dogsList.add("Alaskan Klee Kai::2");
  39. dogsList.add("Papillon::3");
  40. dogsList.add("Tibetan Spaniel::4");
  42. // convert to simple array
  43. popUpContents = new String[dogsList.size()];
  44. dogsList.toArray(popUpContents);
  47. // initialize pop up window
  48. popupWindowDogs = popupWindowDogs();
  51. // button on click listener
  53. View.OnClickListener handler = new View.OnClickListener() {
  54. public void onClick(View v) {
  56. switch (v.getId()) {
  58. case R.id.buttonShowDropDown:
  59. // show the list view as dropdown
  60. popupWindowDogs.showAsDropDown(v, -5, 0);
  61. break;
  62. }
  63. }
  64. };
  66. // our button
  67. buttonShowDropDown = (Button) findViewById(R.id.buttonShowDropDown);
  68. buttonShowDropDown.setOnClickListener(handler);
  69. }
  71. public PopupWindow popupWindowDogs() {
  73. // initialize a pop up window type
  74. PopupWindow popupWindow = new PopupWindow(this);
  76. // the drop down list is a list view
  77. ListView listViewDogs = new ListView(this);
  79. // set our adapter and pass our pop up window contents
  80. listViewDogs.setAdapter(dogsAdapter(popUpContents));
  82. // set the item click listener
  83. listViewDogs.setOnItemClickListener(new DogsDropdownOnItemClickListener());
  85. // some other visual settings
  86. popupWindow.setFocusable(true);
  87. popupWindow.setWidth(250);
  88. popupWindow.setHeight(WindowManager.LayoutParams.WRAP_CONTENT);
  90. // set the list view as pop up window content
  91. popupWindow.setContentView(listViewDogs);
  93. return popupWindow;
  94. }
  96. /*
  97. * adapter where the list values will be set
  98. */
  99. private ArrayAdapter<String> dogsAdapter(String dogsArray[]) {
  101. ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, dogsArray) {
  103. @Override
  104. public View getView(int position, View convertView, ViewGroup parent) {
  106. // setting the ID and text for every items in the list
  107. String item = getItem(position);
  108. String[] itemArr = item.split("::");
  109. String text = itemArr[0];
  110. String id = itemArr[1];
  112. // visual settings for the list item
  113. TextView listItem = new TextView(MainActivity.this);
  115. listItem.setText(text);
  116. listItem.setTag(id);
  117. listItem.setTextSize(22);
  118. listItem.setPadding(10, 10, 10, 10);
  119. listItem.setTextColor(Color.WHITE);
  121. return listItem;
  122. }
  123. };
  125. return adapter;
  126. }
  127. }
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.
  1. package com.example.showasdropdownexample;
  3. import android.content.Context;
  4. import android.view.View;
  5. import android.view.animation.Animation;
  6. import android.view.animation.AnimationUtils;
  7. import android.widget.AdapterView;
  8. import android.widget.Toast;
  9. import android.widget.AdapterView.OnItemClickListener;
  10. import android.widget.TextView;
  12. public class DogsDropdownOnItemClickListener implements OnItemClickListener {
  14. String TAG = "DogsDropdownOnItemClickListener.java";
  16. @Override
  17. public void onItemClick(AdapterView<?> arg0, View v, int arg2, long arg3) {
  19. // get the context and main activity to access variables
  20. Context mContext = v.getContext();
  21. MainActivity mainActivity = ((MainActivity) mContext);
  23. // add some animation when a list item was clicked
  24. Animation fadeInAnimation = AnimationUtils.loadAnimation(v.getContext(), android.R.anim.fade_in);
  25. fadeInAnimation.setDuration(10);
  26. v.startAnimation(fadeInAnimation);
  28. // dismiss the pop up
  29. mainActivity.popupWindowDogs.dismiss();
  31. // get the text and set it as the button text
  32. String selectedItemText = ((TextView) v).getText().toString();
  33. mainActivity.buttonShowDropDown.setText(selectedItemText);
  35. // get the id
  36. String selectedItemTag = ((TextView) v).getTag().toString();
  37. Toast.makeText(mContext, "Dog ID is: " + selectedItemTag, Toast.LENGTH_SHORT).show();
  39. }
  41. }
activity_main.xml – Here is the XML layout file we used for the user interface of our example.
  1. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  2. xmlns:tools="http://schemas.android.com/tools"
  3. android:layout_width="match_parent"
  4. android:layout_height="match_parent"
  5. android:paddingBottom="@dimen/activity_vertical_margin"
  6. android:paddingLeft="@dimen/activity_horizontal_margin"
  7. android:paddingRight="@dimen/activity_horizontal_margin"
  8. android:paddingTop="@dimen/activity_vertical_margin"
  9. tools:context=".MainActivity" >
  11. <Button
  12. android:id="@+id/buttonShowDropDown"
  13. android:layout_width="wrap_content"
  14. android:layout_height="wrap_content"
  15. android:layout_centerHorizontal="true"
  16. android:layout_centerVertical="true"
  17. android:text="Select your dog..." />
  19. </RelativeLayout>