Android control: Use the drop-down list box -- Spinner

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I. Previous Code

<Spinner android: id = "@ + id/spin" android: paddingTop = "10px" android: layout_width = "fill_parent" android: layout_height = "50sp"/> <Button android: id = "@ + id/addList" android: layout_width = "wrap_content" android: layout_height = "wrap_content" android: text = "add"/>

2. Create a New View resource in the drop-down list, that is, the TextView of each Item. we name it dropdown. xml and place it in drawable. The code is:

<?xml version="1.0" encoding="utf-8"?><TextView xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/tv1"    android:layout_width="fill_parent"    android:layout_height="20sp"    android:singleLine="true"    style="?android:attr/spinnerDropDownItemStyle"    />

3. Create an Adapter

Here we will introduce two functions:

1. ArrayAdapter. ArrayAdapter (Context context, int textViewResourcId, List <String> objects)

We can use it to create a new Adapter object. Three parameters are required:

(1) context is the Activity and application of the Adapter.

(2) Resource id of textViewResourcId TextView

(3) The last parameter is the data you want to add to the drop-down List. It can be a static String array or a dynamic List <String>;

2. AdapterView. setOnItemSelectedListener (OnItemSelectedListener listener). This method is used to set a listener for the Spinner object. The parameter here is the OnItemSelectedListener interface, which requires two methods to be rewritten:

(1) public void onItemSelected (AdapterView <?> Parent, View view,Int position, long id)

This method can be used to complete the processing when the option is selected. Meanings of the four parameters:

• AdapterView <?> Parent. This is similar to context. It only indicates the AdapterView of your current operation in the range comparison.
• View view. This parameter is the TextView object you click.
• The int position parameter indicates the position of the view you clicked in the entire AdaterView.
• Long id click the view id

(2) public void onNothingSelected (AdapterView <?> Parent)

This callback function is called when no options are available in AdapterView.

The complete code is as follows:

Private Spinner spinner; private TextView TV; private ArrayAdapter <String> adapter; private static final String [] years = {"less than 1 year", "1-3 years ", "3-5 years", "more than 5 years"}; private ArrayList <String> array = new ArrayList <String> (); @ Override protected void onCreate (Bundle savedInstanceState) {super. onCreate (savedInstanceState); setContentView (R. layout. activity_main); if (savedInstanceState = null) {getSuppor TFragmentManager (). beginTransaction (). add (R. id. container, new PlaceholderFragment ()). commit ();} spinner = (Spinner) findViewById (R. id. spin); TV = (TextView) findViewById (R. id. textView1); for (int I = 0; I <years. length; I ++) {array. add (years [I]);} adapter = new ArrayAdapter <String> (this, android. r. layout. simple_spinner_item, array); adapter. setDropDownViewResource (R. drawable. dropdown); spinne R. setAdapter (adapter); spinner. setOnItemSelectedListener (new OnItemSelectedListener () {@ Override public void onItemSelected (AdapterView <?> Parent, View view, int position, long id) {// TODO automatically generated method stub String seleted = array. get (position); TV. setText (seleted); parent. setVisibility (View. VISIBLE) ;}@ Override public void onNothingSelected (AdapterView <?> Arg0) {// TODO automatically generated method stub TV. setText ("You have not selected ");}});

 

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