Use of components (i) Use of spinner

Spinner is the drop-down menu.

Implementing the Spinner component in Android requires the following three steps:

1. Define the label in the XML file spinner

<Spinner  android:id="@+id/spinner"  android:layout_width="match_parent"  android:layout_height="wrap_content"  <!--其它属性略-->  />

2. Declare items in the Strings.xml file

<resources ;  <string  name  = "item1" ;  item1</string   <string  name  = "item2" ;  item2</ string ;  <string  name  = "Item3" ;  Item3</string ;  <!-- other item omitted-->  </rresources ;  

3.Java Code Implementation Controller
We need baseadapter to pass string data to the spinner UI component, and implementation Baseadapter must override some methods.
Examples of code slices:

//Data fieldsSpinner Spinner;int[] messageids={r.string.item1,r.string.item2,r.string.item3};//drop-down menu spinner Items Resources        //Cover OnCreate () method        @Override         Public void onCreate(Bundle savedinstancestate) { This. Requestwindowfeature (Window.feature_no_title);//Remove title bar            Super. OnCreate (Savedinstancestate);            Setcontentview (R.layout.register); Processspinner ();//Processing drop-down menu spinner}//This method is used to process the drop-down list spinner        Private void Processspinner() {spinner= (spinner) Findviewbyid (R.id.spinner);//adapter as an adapter for spinnerBaseadapter baseadapter=NewBaseadapter () {@Override                 PublicViewGetView(intPosition, View Convertview, ViewGroup parent) {TextView spinneritemtextview=NewTextView (Register. This); Spinneritemtextview.settext ("    "+getresources (). GetText (Messageids[position]);                    Spinneritemtextview.settextcolor (Color.Black); Spinneritemtextview.settextsize ( -);returnSpinneritemtextview; }@Override                 Public Long Getitemid(intARG0) {//TODO auto-generated method stub                    return 0; }@Override                 PublicObjectGetItem(intARG0) {//TODO auto-generated method stub                    return NULL; }@Override                 Public int GetCount() {//TODO auto-generated method stub                    return 3;            }            }; Spinner.setadapter (Baseadapter);//Set adapter for spinner}

If you want to set a click event for spinner items, you can do this:

spinner.setonitemselectedlistener (new  Onitemselectedlistener () { @Override  public  void  onitemselected  (adapterview<? > Parent, view view, int  position, long  ID) {String str=parent.getitematposition (position). ToString (); Toast.maketext (Spinneractivity. This ,  "you clicked:"  +str, 2000 ). Show (); }  @Override  public  void  onnothingselected  (adapterview<?> parent) {//TODO auto-generated Method stub }}); 

Attention:
In fact, a string resource can also be written in another form:

<stringname="spinnername">        <item>北京</item>        <item>上海 </item>        <item>广州</item>        <item>深圳</item>    </string-array>

In the corresponding Java code, a string array is created instead of a string ID array.

// 建立String数组存储Spinner数据String[] mItems = getResources().getStringArray(R.array.spinnername);

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Use of components (i) Use of spinner