Android: Use of the Spinner (drop-down box) control.

Android: Use of the Spinner (drop-down box) control.

Android: Use of the Spinner (drop-down box) Control

Create a page file (main. xml)

1 <Spinner

2 android: id = "@ + id/spinner1"

3 android: layout_width = "match_parent"

4 android: layout_height = "wrap_content"/>

5

6 <TextView

7 android: id = "@ + id/tvResult"

8 android: layout_width = "match_parent"

9 android: layout_height = "wrap_content"

10 android: text = "selected fruit"/>

 

Create a data source from the drop-down list

 

1 List <String> list = new ArrayList <String> ();

2 list. add ("apple ");

5 list. add ("banana ");

7 list. add ("orange ");

9 list. add ("banana ");

 

Create an adapter (the data source in the drop-down list is from the adapter)

 

ArrayAdapter <String> adapter = new ArrayAdapter <String> (this, android. R. layout. simple_spinner_item, list );

Add a style for the adapter

 

Adapter. setDropDownViewResource (android. R. layout. simple_spinner_dropdown_item );

 

The system provides the following styles:

 

L simple_spinner_dropdown_item (list-relatively nice-looking with high spacing)

 

Clip_image004 [10]

 

L simple_spinner_item (list-compact spacing is hard to see)

 

Clip_image006 [10]

 

L simple_list_item_checked (check box-selected green ditch)

 

Clip_image008 [10]

 

L simple_list_item_single_choice (single choice button)

 

Clip_image010 [10]

 

Add an adapter to the control Spinner

 

1 Spinner sp = (Spinner) findViewById (R. id. spinner1 );

2 sp. setAdapter (adapter );

 

Meaning

 

1. setAdapter (SpinnerAdapter adapter). From the inheritance relationship of the class, ArrayAdapter is an indirect implementation class of the SpinnerAdapter interface.

 

Clip_image012 [10]

 

Implement the selected event (using an anonymous class to implement the interface)

 

1 sp. setOnItemSelectedListener (new OnItemSelectedListener (){

2 // parent: For the control Spinner view: TextView position of the displayed text: the position of the drop-down option starts from 0

3 public void onItemSelected (AdapterView <?> Parent, View view, int position, long id ){

4 TextView tvResult = (TextView) findViewById (R. id. tvResult );

5 // obtain the adapter of the Spinner Control

6 ArrayAdapter <String> adapter = (ArrayAdapter <String>) parent. getAdapter ();

7 tvResult. setText (adapter. getItem (position ));

8}

9 // processing when no selection is made

10 public void onNothingSelected (AdapterView <?> Parent ){

11}

12 });

 

The overall background code is as follows:

 

1 public void onCreate (Bundle savedInstanceState ){

2 super. onCreate (savedInstanceState );

3 setContentView (R. layout. main );

4 List <String> list = new ArrayList <String> ();

5 list. add ("apple ");

6 list. add ("banana ");

7 list. add ("orange ");

8 list. add ("banana ");

9 ArrayAdapter <String> adapter = new ArrayAdapter <String> (this, android. R. layout. simple_spinner_item, list );

10 adapter. setDropDownViewResource (android. R. layout. simple_list_item_single_choice );

11 Spinner sp = (Spinner) findViewById (R. id. spinner1 );

12 sp. setAdapter (adapter );

13 sp. setOnItemSelectedListener (new OnItemSelectedListener (){

14 // parent: For the control Spinner view: TextView position of the displayed text: the position of the drop-down option starts from 0

15 public void onItemSelected (AdapterView <?> Parent, View view, int position, long id ){

16 TextView tvResult = (TextView) findViewById (R. id. tvResult );

17 // get the adapter of the Spinner Control

18 ArrayAdapter <String> adapter = (ArrayAdapter <String>) parent. getAdapter ();

19 tvResult. setText (adapter. getItem (position ));

20}

21 // processing when no selection is made

22 public void onNothingSelected (AdapterView <?> Parent ){

23}

24 });

25}