Android Basic---->spinner use

　　Spinner provides a quick way to select values from the collection. By default, a spinner displays the values that are currently selected. Touch Spinner displays a drop-down menu from which the user can select a value. Today we begin to spinner study.

The project structure is as follows:

Define a spinner in the XML file, as follows:

< Spinner     Android:id = "@+id/spinner"     android:layout_width= "Wrap_content"    android:layout_height= "Wrap_ Content "/>

To add a selection list to spinner, you need to specify a spinneradapter in your activity or fragment code.

Add a selection list to the spinner

The list content in spinner can come from any source, but requires a spinneradapter, such as if the selection is an array, then adapter is Arrayadapter, or the selection is from a database query, Then adapter is CursorAdapter.

For example, if the selection is predetermined, you can specify an array content in the string's resource file.

<?XML version= "1.0" encoding= "Utf-8"?><Resources>    <String-arrayname= "Spinner_array">        <Item>Linux</Item>        <Item>Huhx</Item>        <Item>Liuli</Item>        <Item>Chenhui</Item>        <Item>Android</Item>    </String-array></Resources>

Provide an example of a arrayadapter in activity or fragment, as follows:

Spinner = (spinner) Findviewbyid (R.id.spinner); Arrayadapter<CharSequence> adapter = Arrayadapter.createfromresource (this, R.array.spinner _array, Android. R.layout.simple_spinner_item); Adapter.setdropdownviewresource (R.layout.support_simple_spinner_dropdown_item); Spinner.setadapter (adapter);

The Createfromresource method allows you to create a arrayadapter from a character array. The second parameter is an array defined in the resource file, and the third parameter is the way to define the spinner selection. simple_spinner_item. XML is as follows:

<?XML version= "1.0" encoding= "Utf-8"?><TextViewxmlns:android= "Http://schemas.android.com/apk/res/android"Android:id= "@android: Id/text1"style= "? Android:attr/spinneritemstyle"Android:singleline= "true"Android:layout_width= "Match_parent"Android:layout_height= "Wrap_content"android:ellipsize= "Marquee"android:textalignment= "Inherit"/>

then you need to call the Setdropdownviewresource method to specify the layout in the spinner list: Support_simple_spinner_dropdown_item.xml as follows:

<?XML version= "1.0" encoding= "Utf-8"?><TextViewxmlns:android= "Http://schemas.android.com/apk/res/android"Android:id= "@android: Id/text1"style= "? Attr/spinnerdropdownitemstyle"Android:singleline= "true"Android:layout_width= "Match_parent"Android:layout_height= "? Attr/dropdownlistpreferreditemheight"android:ellipsize= "Marquee"/>

responding to user-selected spinner events

When the user selects a row in the drop-down menu, the spinner object receives a on-item-selected event:

Spinner.setonitemselectedlistener (new  Adapterview.onitemselectedlistener () {    @Override    public voidintlong  id) {        "Viewa:" + View + ", Parent:" + parent + " , Position: "+ position +", ID: "+ ID";    }    @Override    publicvoid onnothingselected (adapterview<?> parent) {        "on Nothing Selected");    });

The results are as follows:

Use of Android Foundation---->spinner