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

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

Create a paging 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"

Ten android:text= "Fruit of choice"/>

Create a data source for a drop-down box

1 list<string> List = new arraylist<string> ();

2 List.add ("Apple");

5 List.add ("banana");

7 List.add ("Orange");

9 List.add ("banana");

Create adapter (the data source for the drop-down box is from the adapter)

Arrayadapter<string> adapter=new arrayadapter<string> (this, Android. R.layout.simple_spinner_item,list);

To add a style to an adapter

Adapter.setdropdownviewresource (Android. R.layout.simple_spinner_dropdown_item);

The system provides the following styles

L Simple_spinner_dropdown_item (List-higher spacing more beautiful)

CLIP_IMAGE004[10]

L Simple_spinner_item (List-tight spacing is not good to see)

CLIP_IMAGE006[10]

L simple_list_item_checked (check box-Green ditch selected)

CLIP_IMAGE008[10]

L Simple_list_item_single_choice (radio button)

CLIP_IMAGE010[10]

Adding an adapter to a control spinner

1 Spinner sp= (Spinner) Findviewbyid (r.id.spinner1);

2 Sp.setadapter (adapter);

Interpretation

1. Setadapter (Spinneradapter adapter), Arrayadapter is an indirect implementation class of the Spinneradapter interface from the inheritance relationship of the class

CLIP_IMAGE012[10]

Implementing a Selection event (implementing an interface using an anonymous class)

1 Sp.setonitemselectedlistener (new Onitemselectedlistener () {

2//Parent: Spinner View for controls: TextView position for display text: The position of the drop-down option starts at 0

3 public void onitemselected (adapterview<?> parent, view view, int position, long ID) {

4 TextView Tvresult = (TextView) Findviewbyid (R.id.tvresult);

5//Get the adapter for the spinner control

6 Arrayadapter<string> adapter = (arrayadapter<string>) parent.getadapter ();

7 Tvresult.settext (Adapter.getitem (position));

8}

9//No processing when unchecked

Ten public void onnothingselected (adapterview<?> parent) {

11}

12});

Background overall 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);

Ten Adapter.setdropdownviewresource (Android. R.layout.simple_list_item_single_choice);

Spinner sp = (Spinner) Findviewbyid (r.id.spinner1);

Sp.setadapter (adapter);

Sp.setonitemselectedlistener (New Onitemselectedlistener () {

+//Parent: Spinner View for controls: TextView position for display text: The position of the drop-down option starts at 0

public void onitemselected (adapterview<?> parent, view view, int position, long ID) {

TextView Tvresult = (TextView) Findviewbyid (R.id.tvresult);

17//Get the adapter for the spinner control

arrayadapter<string> adapter = (arrayadapter<string>) parent.getadapter ();

Tvresult.settext (Adapter.getitem (position));

20}

21//No processing when unchecked

public void onnothingselected (adapterview<?> parent) {

23}

24});

25}

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