Quello che puoi fare è decorare il tuo SpinnerAdaptercon uno che presenta una 'Seleziona opzione ...' Inizialmente per la visualizzazione dello Spinner con niente selezionato.
Ecco un esempio funzionante testato per Android 2.3 e 4.0 (non utilizza nulla nella libreria di compatibilità, quindi dovrebbe andare bene per un po ') Dato che è un decoratore, dovrebbe essere facile aggiornare il codice esistente e funziona bene anche con CursorLoaders. (Scambia il cursore sull'involucro cursorAdapterovviamente ...)
Esiste un bug Android che rende un po 'più difficile riutilizzare le visualizzazioni. (Quindi devi usare setTago qualcos'altro per assicurarti che convertViewsia corretto.) Spinner non supporta più tipi di vista
Note di codice: 2 costruttori
Ciò consente di utilizzare un prompt standard o di definire il proprio "niente selezionato" come prima riga, o entrambi o nessuno. (Nota: alcuni temi mostrano un DropDown per uno Spinner anziché una finestra di dialogo. Il menu a discesa normalmente non mostra il prompt)
Definisci un layout per "sembrare" come un prompt, ad esempio, disattivato ...
Utilizzando un prompt standard (notare che non è selezionato nulla):
O con un prompt e qualcosa di dinamico (non avrebbe potuto avere anche un prompt):
Utilizzo nell'esempio sopra
Spinner spinner = (Spinner) findViewById(R.id.spinner);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.planets_array, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setPrompt("Select your favorite Planet!");
spinner.setAdapter(
new NothingSelectedSpinnerAdapter(
adapter,
R.layout.contact_spinner_row_nothing_selected,
// R.layout.contact_spinner_nothing_selected_dropdown, // Optional
this));
contact_spinner_row_nothing_selected.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns: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:textSize="18sp"
android:textColor="#808080"
android:text="[Select a Planet...]" />
NothingSelectedSpinnerAdapter.java
import android.content.Context;
import android.database.DataSetObserver;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.SpinnerAdapter;
/**
* Decorator Adapter to allow a Spinner to show a 'Nothing Selected...' initially
* displayed instead of the first choice in the Adapter.
*/
public class NothingSelectedSpinnerAdapter implements SpinnerAdapter, ListAdapter {
protected static final int EXTRA = 1;
protected SpinnerAdapter adapter;
protected Context context;
protected int nothingSelectedLayout;
protected int nothingSelectedDropdownLayout;
protected LayoutInflater layoutInflater;
/**
* Use this constructor to have NO 'Select One...' item, instead use
* the standard prompt or nothing at all.
* @param spinnerAdapter wrapped Adapter.
* @param nothingSelectedLayout layout for nothing selected, perhaps
* you want text grayed out like a prompt...
* @param context
*/
public NothingSelectedSpinnerAdapter(
SpinnerAdapter spinnerAdapter,
int nothingSelectedLayout, Context context) {
this(spinnerAdapter, nothingSelectedLayout, -1, context);
}
/**
* Use this constructor to Define your 'Select One...' layout as the first
* row in the returned choices.
* If you do this, you probably don't want a prompt on your spinner or it'll
* have two 'Select' rows.
* @param spinnerAdapter wrapped Adapter. Should probably return false for isEnabled(0)
* @param nothingSelectedLayout layout for nothing selected, perhaps you want
* text grayed out like a prompt...
* @param nothingSelectedDropdownLayout layout for your 'Select an Item...' in
* the dropdown.
* @param context
*/
public NothingSelectedSpinnerAdapter(SpinnerAdapter spinnerAdapter,
int nothingSelectedLayout, int nothingSelectedDropdownLayout, Context context) {
this.adapter = spinnerAdapter;
this.context = context;
this.nothingSelectedLayout = nothingSelectedLayout;
this.nothingSelectedDropdownLayout = nothingSelectedDropdownLayout;
layoutInflater = LayoutInflater.from(context);
}
@Override
public final View getView(int position, View convertView, ViewGroup parent) {
// This provides the View for the Selected Item in the Spinner, not
// the dropdown (unless dropdownView is not set).
if (position == 0) {
return getNothingSelectedView(parent);
}
return adapter.getView(position - EXTRA, null, parent); // Could re-use
// the convertView if possible.
}
/**
* View to show in Spinner with Nothing Selected
* Override this to do something dynamic... e.g. "37 Options Found"
* @param parent
* @return
*/
protected View getNothingSelectedView(ViewGroup parent) {
return layoutInflater.inflate(nothingSelectedLayout, parent, false);
}
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {
// Android BUG! http://code.google.com/p/android/issues/detail?id=17128 -
// Spinner does not support multiple view types
if (position == 0) {
return nothingSelectedDropdownLayout == -1 ?
new View(context) :
getNothingSelectedDropdownView(parent);
}
// Could re-use the convertView if possible, use setTag...
return adapter.getDropDownView(position - EXTRA, null, parent);
}
/**
* Override this to do something dynamic... For example, "Pick your favorite
* of these 37".
* @param parent
* @return
*/
protected View getNothingSelectedDropdownView(ViewGroup parent) {
return layoutInflater.inflate(nothingSelectedDropdownLayout, parent, false);
}
@Override
public int getCount() {
int count = adapter.getCount();
return count == 0 ? 0 : count + EXTRA;
}
@Override
public Object getItem(int position) {
return position == 0 ? null : adapter.getItem(position - EXTRA);
}
@Override
public int getItemViewType(int position) {
return 0;
}
@Override
public int getViewTypeCount() {
return 1;
}
@Override
public long getItemId(int position) {
return position >= EXTRA ? adapter.getItemId(position - EXTRA) : position - EXTRA;
}
@Override
public boolean hasStableIds() {
return adapter.hasStableIds();
}
@Override
public boolean isEmpty() {
return adapter.isEmpty();
}
@Override
public void registerDataSetObserver(DataSetObserver observer) {
adapter.registerDataSetObserver(observer);
}
@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
adapter.unregisterDataSetObserver(observer);
}
@Override
public boolean areAllItemsEnabled() {
return false;
}
@Override
public boolean isEnabled(int position) {
return position != 0; // Don't allow the 'nothing selected'
// item to be picked.
}
}
