1 page.title=Hello, Spinner 2 parent.title=Hello, Views 3 parent.link=index.html 4 @jd:body 5 6 <p>A {@link android.widget.Spinner} is a widget that allows the user to select an item from a group. 7 It is similar to a dropdown list and will allow scrolling when the 8 list exceeds the available vertical space on the screen.</p> 9 10 11 <ol> 12 <li>Start a new project/Activity called HelloSpinner.</li> 13 <li>Open the layout file. 14 Make it like so: 15 <pre> 16 <?xml version="1.0" encoding="utf-8"?> 17 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 18 android:orientation="vertical" 19 android:padding="10dip" 20 android:layout_width="fill_parent" 21 android:layout_height="wrap_content"> 22 23 <TextView 24 android:layout_width="fill_parent" 25 android:layout_height="wrap_content" 26 android:layout_marginTop="10dip" 27 android:text="Please select a planet:" 28 /> 29 30 <Spinner 31 android:id="@+id/spinner" 32 android:layout_width="fill_parent" 33 android:layout_height="wrap_content" 34 android:drawSelectorOnTop="true" 35 android:prompt="@string/planet_prompt" 36 /> 37 38 </LinearLayout> 39 </pre> 40 <p>Notice that the Spinner's <code>android:prompt</code> is a string resource. In 41 this case, Android does not allow it to be a string, it must be a reference to a resource. 42 So...</p> 43 </li> 44 45 <li>Open the strings.xml file in res/values/ and add the following <code><string></code> 46 element inside the <code><resources></code> element: 47 <pre> 48 <string name="planet_prompt">Choose a planet</string> 49 </pre> 50 </li> 51 52 <li>Create a new XML file in res/values/ called arrays.xml. Insert the following: 53 <pre> 54 <resources> 55 56 <string-array name="planets"> 57 <item>Mercury</item> 58 <item>Venus</item> 59 <item>Earth</item> 60 <item>Mars</item> 61 <item>Jupiter</item> 62 <item>Saturn</item> 63 <item>Uranus</item> 64 <item>Neptune</item> 65 </string-array> 66 67 </resources> 68 </pre> 69 <p>This is the list of items (planets) that the user can select from in the Spinner widget.</p> 70 </li> 71 72 <li>Now open the HelloSpinner.java file. Insert the following code into the HelloSpinner class: 73 <pre> 74 @Override 75 public void onCreate(Bundle savedInstanceState) { 76 super.onCreate(savedInstanceState); 77 setContentView(R.layout.main); 78 79 Spinner s = (Spinner) findViewById(R.id.spinner); 80 ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource( 81 this, R.array.planets, android.R.layout.simple_spinner_item); 82 adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); 83 s.setAdapter(adapter); 84 } 85 </pre> 86 <p>That's it. We start by creating a Spinner from our layout. We then create an {@link android.widget.ArrayAdapter} 87 that binds each element of our string array to a layout view—we pass <code>createFromResource</code> our Context, 88 the array of selectable items and the type of layout we'd like each one bound to. We then call 89 <code>setDropDownViewResource()</code> to define the type of layout in which to present the 90 entire collection. Finally, we set this Adapter to associate with our Spinner, 91 so the string items have a place to go.</p> 92 </li> 93 94 <li>Now run it.</li> 95 </ol> 96 <p>It should look like this:</p> 97 <img src="images/hello-spinner.png" width="150px" /> 98 99 100 <h3>Resources</h3> 101 <ul> 102 <li>{@link android.R.layout}</li> 103 <li>{@link android.widget.ArrayAdapter}</li> 104 <li>{@link android.widget.Spinner}</li> 105 </ul> 106 107
