如何使一个Android旋转与初始文本"选择"?

小开

首先，您可能对Spinner类的prompt属性感兴趣。见下图，“Choose a Planet”是可以在XML中使用android:prompt=""设置的提示符。

我建议继承Spinner的子类，在那里您可以在内部维护两个适配器。一个适配器具有“Select One”选项，另一个真正的适配器(具有实际的选项)，然后在显示选项对话框之前使用OnClickListener来切换适配器。然而，在尝试实现这个想法之后，我得出的结论是，小部件本身不能接收OnClick事件。

您可以将旋转器包装在不同的视图中，拦截视图上的单击，然后告诉CustomSpinner切换适配器，但这似乎是一种糟糕的hack。

你真的需要显示“选择一”吗?

小开

我找到了这个解决方案:

String[] items = new String[] {"Select One", "Two", "Three"};
Spinner spinner = (Spinner) findViewById(R.id.mySpinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_item, items);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);


spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long id) {
items[0] = "One";
selectedItem = items[position];
}


@Override
public void onNothingSelected(AdapterView<?> arg0) {
}
});

只需用“Select One”更改数组[0]，然后在onItemSelected中，将其重命名为“One”。

这不是一个很好的解决方案，但它是有效的

小开

最佳答案

下面是一个覆盖Spinner视图的通用解决方案。它覆盖setAdapter()以将初始位置设置为-1，并代理提供的SpinnerAdapter以显示位置小于0的提示字符串。

这已经在Android 1.5到4.2上进行了测试，但买家要小心!因为这个解决方案依赖于反射来调用私有的AdapterView.setNextSelectedPositionInt()和AdapterView.setSelectedPositionInt()，所以它不能保证在未来的操作系统更新中工作。这似乎是有可能的，但这绝不是保证的。

通常我不会宽恕这样的事情，但这个问题已经被问了很多次了，这似乎是一个足够合理的要求，我认为我应该发布我的解决方案。

/**
* A modified Spinner that doesn't automatically select the first entry in the list.
*
* Shows the prompt if nothing is selected.
*
* Limitations: does not display prompt if the entry list is empty.
*/
public class NoDefaultSpinner extends Spinner {


public NoDefaultSpinner(Context context) {
super(context);
}


public NoDefaultSpinner(Context context, AttributeSet attrs) {
super(context, attrs);
}


public NoDefaultSpinner(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}


@Override
public void setAdapter(SpinnerAdapter orig ) {
final SpinnerAdapter adapter = newProxy(orig);


super.setAdapter(adapter);


try {
final Method m = AdapterView.class.getDeclaredMethod(
"setNextSelectedPositionInt",int.class);
m.setAccessible(true);
m.invoke(this,-1);


final Method n = AdapterView.class.getDeclaredMethod(
"setSelectedPositionInt",int.class);
n.setAccessible(true);
n.invoke(this,-1);
}
catch( Exception e ) {
throw new RuntimeException(e);
}
}


protected SpinnerAdapter newProxy(SpinnerAdapter obj) {
return (SpinnerAdapter) java.lang.reflect.Proxy.newProxyInstance(
obj.getClass().getClassLoader(),
new Class[]{SpinnerAdapter.class},
new SpinnerAdapterProxy(obj));
}






/**
* Intercepts getView() to display the prompt if position < 0
*/
protected class SpinnerAdapterProxy implements InvocationHandler {


protected SpinnerAdapter obj;
protected Method getView;




protected SpinnerAdapterProxy(SpinnerAdapter obj) {
this.obj = obj;
try {
this.getView = SpinnerAdapter.class.getMethod(
"getView",int.class,View.class,ViewGroup.class);
}
catch( Exception e ) {
throw new RuntimeException(e);
}
}


public Object invoke(Object proxy, Method m, Object[] args) throws Throwable {
try {
return m.equals(getView) &&
(Integer)(args[0])<0 ?
getView((Integer)args[0],(View)args[1],(ViewGroup)args[2]) :
m.invoke(obj, args);
}
catch (InvocationTargetException e) {
throw e.getTargetException();
}
catch (Exception e) {
throw new RuntimeException(e);
}
}


protected View getView(int position, View convertView, ViewGroup parent)
throws IllegalAccessException {


if( position<0 ) {
final TextView v =
(TextView) ((LayoutInflater)getContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE)).inflate(
android.R.layout.simple_spinner_item,parent,false);
v.setText(getPrompt());
return v;
}
return obj.getView(position,convertView,parent);
}
}
}

小开

我得到了同样的问题旋转，与一个空的选择，我找到了一个更好的解决方案。看看这段简单的代码。

Spinner lCreditOrDebit = (Spinner)lCardPayView.findViewById(R.id.CARD_TYPE);
spinneradapter lAdapter =
new spinneradapter(
BillPayScreen.this,
ndroid.R.layout.simple_spinner_item,getResources().getStringArray(R.array.creditordebit));
lAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
lCreditOrDebit.setAdapter(lAdapter);

这里spinneradapter是对arrayadapter的一个小定制。它是这样的:

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;


public class spinneradapter extends ArrayAdapter<String>{
private Context m_cContext;
public spinneradapter(Context context,int textViewResourceId, String[] objects) {
super(context, textViewResourceId, objects);
this.m_cContext = context;
}


boolean firsttime = true;
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(firsttime){
firsttime = false;
//Just return some empty view
return new ImageView(m_cContext);
}
//Let the array adapter take care of it this time.
return super.getView(position, convertView, parent);
}
}

小开

XML文件:

<Spinner android:id="@+id/locationSpinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:prompt="@string/select_location" />

活动:

private Spinner featuresSelection;
private ArrayAdapter<CharSequence> featuresAdapter;
private List<CharSequence> featuresList;

onCreate:

featuresList = new ArrayList<CharSequence>();
featuresAdapter = new ArrayAdapter<CharSequence>(this,
android.R.layout.simple_spinner_item, featuresList);
featuresAdapter.setDropDownViewResource(
android.R.layout.simple_spinner_dropdown_item);
featuresSelection = ((Spinner) yourActivity.this
.findViewById(R.id.locationSpinner));
featuresSelection.setAdapter(featuresAdapter);
featuresSelection.setOnItemSelectedListener(
new MyOnItemSelectedListener());

某些函数(以编程方式向适配器添加内容)>

featuresAdapter.add("some string");

现在你有一个空的转轮，你可以写代码不打开对话框，如果是空的。或者他们可以反击。但是您也可以在运行时用函数或另一个列表填充它。

小开

我最终使用Button代替。虽然Button不是Spinner，但行为很容易自定义。

首先像往常一样创建适配器:

String[] items = new String[] {"One", "Two", "Three"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_dropdown_item, items);

注意，我使用simple_spinner_dropdown_item作为布局id。这将有助于创建一个更好的外观时，创建警报对话框。

在onClick处理我的按钮，我有:

public void onClick(View w) {
new AlertDialog.Builder(this)
.setTitle("the prompt")
.setAdapter(adapter, new DialogInterface.OnClickListener() {


@Override
public void onClick(DialogInterface dialog, int which) {


// TODO: user specific action


dialog.dismiss();
}
}).create().show();
}

就是这样!

小开

如果你只有三个选择，我只会使用带有RadioButtons的RadioGroup，你可以在一开始让它们都未选中。

小开

看一下iosched应用程序，它提供了一个通用的解决方案，可以将元素添加到列表的顶部。特别是，如果您正在使用CursorAdapter，请查看TracksAdapter.java，它扩展了该定义以提供“setHasAllItem”方法和相关代码来管理列表计数，以处理顶部的额外项目。

使用自定义适配器，您可以将文本设置为“Select One”或其他任何您希望顶部项目显示的内容。

小开

我在main.xml中有一个旋转器，它的id是@+id/spinner1

这是我在OnCreate函数中写的:

spinner1 = (Spinner)this.findViewById(R.id.spinner1);
final String[] groupes = new String[] {"A", "B", "C", "D", "E", "F", "G", "H"};
ArrayAdapter<CharSequence> featuresAdapter = new ArrayAdapter<CharSequence>(this, android.R.layout.simple_spinner_item, new ArrayList<CharSequence>());
featuresAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner1.setAdapter(featuresAdapter);
for (String s : groupes) featuresAdapter.add(s);


spinner1.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long id) {
// Here go your instructions when the user chose something
Toast.makeText(getBaseContext(), groupes[position], 0).show();
}
public void onNothingSelected(AdapterView<?> arg0) { }
});

它不需要类中的任何实现。

小开

我试过的方法如下。取一个按钮并将单击事件赋予它。通过改变按钮背景，它似乎是一个旋转器。

声明为全局变量alertdialog和默认值..

AlertDialog d;
static int default_value = 0;
final Button btn = (Button) findViewById(R.id.button1);
btn .setOnClickListener(new View.OnClickListener() {


@Override
public void onClick(View v)
{
//c.show();
final CharSequence str[] = {"Android","Black Berry","Iphone"};
AlertDialog.Builder builder =
new AlertDialog.Builder(TestGalleryActivity.this).setSingleChoiceItems(
str, default_value,new  DialogInterface.OnClickListener() {


@Override
public void onClick(DialogInterface dialog, int position)
{
Toast.makeText(TestGalleryActivity.this,
"" + position,
Toast.LENGTH_SHORT).show();
default_value = position;
btn.setText(str[position]);
if(d.isShowing())
d.dismiss();
}
}).setTitle("Select Any");
d = builder.create();
d.show();
}
});

小开

我认为最简单的方法是在索引0上创建一个虚拟的项目，输入“select one”，然后在保存时检查是否选择不为0。

小开

当扩展SpinnerAdapter时，您将覆盖两个# eyz1生成方法，getView(int, View, ViewGroup)和getDropDownView(int, View, ViewGroup)。第一个提供了插入到Spinner本身的View;第二个提供下拉列表中的View(顾名思义)。您可以覆盖getView(...)，这样，在项目被选中之前，它会显示包含提示符的TextView;然后，当您检测到一个项目已被选中时，您将其更改为显示与之对应的TextView。

public class PromptingAdapter extends SpinnerAdapter {


//... various code ...


private boolean selectionmade = false;


//call this method from the OnItemSelectedListener for your Spinner
public setSelectionState(boolean b) {
selectionmade = b;
}


@Override
public View getView(int position, View recycle, ViewGroup container) {
if(selectionmade) {
//your existing code to supply a View for the Spinner
//you could even put "return getDropDownView(position, recycle, container);"
}
else {
View output;
if(recycle instanceof TextView) {
output = recycle;
}
else {
output = new TextView();
//and layout stuff
}
output.setText(R.string.please_select_one);
//put a string "please_select_one" in res/values/strings.xml
return output;
}
}


//...
}

小开

你可以做的是装饰你的SpinnerAdapter与一个显示“选择选项…”视图，以便旋转器显示时不选择任何内容。

下面是一个在Android 2.3和4.0上测试的工作示例(它在兼容性库中没有使用任何东西，所以它应该是好的)，因为它是一个装饰器，它应该很容易改造现有的代码，它也可以很好地使用CursorLoaders。(交换光标在被包装的cursorAdapter上当然…)

有一个Android漏洞使得重用视图有点困难。(所以你必须使用setTag或其他东西来确保你的convertView是正确的。

代码注释:2个构造函数

这允许您使用标准提示符或定义您自己的“nothing selected”作为第一行，或两者都有，或没有。(注意:有些主题为旋转器显示下拉菜单，而不是对话框。下拉菜单通常不会显示提示)

你定义了一个“看起来”像提示符的布局，例如，灰色…

Initial nothing selected

使用标准提示符(注意没有选择任何内容):

With a standard prompt .

或者加上提示符和动态的东西(也可以没有提示符):

提示且无选定行 .

上面例子中的用法

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.
}


}

小开

这是我最后一个“all in”按钮旋转器的例子

在# EYZ0

    <Button
android:id="@+id/btnSpinnerPlanets"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="left|center_vertical"
android:singleLine="true"
android:text="@string/selectAPlanet"
android:textSize="10sp"
android:background="@android:drawable/btn_dropdown">
</Button>

在# EYZ0

<string name="selectAPlanet">Select planet&#8230;</string>


<string-array name="planets__entries">
<item>The Sun with a name very long so long long long long longThe Sun with a name very long so long long long long longThe Sun with a name very long so long long long long long</item>
<item>Mercury</item>
<item>Venus</item>
<item>Earth</item>
<item>Mars</item>
<item>Jupiter</item>
<item>Saturn</item>
<item>Uranus</item>
<item>Neptune</item>
</string-array>

在# EYZ0

public class MyFormActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
((Button) findViewById(R.id.btnSpinnerPlanets)).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
final String[] items = view.getResources().getStringArray(R.array.planets__entries);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(MyFormActivity.this, android.R.layout.simple_spinner_dropdown_item, items);
new AlertDialog.Builder(MyFormActivity.this).setTitle("the prompt").setAdapter(adapter, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
((Button) findViewById(R.id.btnSpinnerPlanets)).setText(items[which]);
dialog.dismiss();
}
}).create().show();
}
});


}


}

最后我获得了一个字体大小可配置无第一项可选择的按钮旋转器!! 感谢HRJ

小开

之前提交的答案都没有真正按照我想要的方式解决这个问题。对我来说，理想的解决方案是在旋转器第一次显示时提供“Select One”(或任何初始文本)。当用户点击转轮时，初始文本不应该是显示的下拉框的一部分。

为了使我的特定情况更加复杂，我的旋转器数据来自通过LoaderManager回调加载的游标。

经过大量的实验，我想出了以下解决方案:

public class MyFragment extends Fragment implements
LoaderManager.LoaderCallbacks<Cursor>{


private static final String SPINNER_INIT_VALUE = "Select A Widget";
private Spinner mSpinner;
private int mSpinnerPosition;
private boolean mSpinnerDropDownShowing = false;
private View mSpinnerDropDown;


private MyCursorAdapter mCursorAdapter;


...


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
...


mCursorAdapter = new MyCursorAdapter(getActivity());


mSpinner = (Spinner) rootView.findViewById(R.id.theSpinner);
mSpinner.setOnTouchListener(mSpinnerTouchListener);
mSpinner.setAdapter(mCursorAdapter);


...
}


//Capture the touch events to toggle the spinner's dropdown visibility
private OnTouchListener mSpinnerTouchListener = new View.OnTouchListener() {
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if(mSpinnerDropDown != null && mSpinnerDropDownShowing == false){
mSpinnerDropDownShowing = true;
mSpinnerDropDown.setVisibility(View.VISIBLE);
}
return false;
}
};


//Capture the click event on the spinner drop down items
protected OnClickListener spinnerItemClick = new OnClickListener(){


@Override
public void onClick(View view) {
String widget = ((TextView) view.findViewById(android.R.id.text1)).getText().toString();


if(!widget.equals(SPINNER_INIT_VALUE)){
if(mCursorAdapter != null){
Cursor cursor = mCursorAdapter.getCursor();
if(cursor.moveToFirst()){
while(!cursor.isAfterLast()){
if(widget.equals(cursor.getString(WidgetQuery.WIDGET_NAME))){


...


//Set the spinner to the correct item
mSpinnerPosition = cursor.getPosition() + 1;
mSpinner.setSelection(mSpinnerPosition);
break;
}
cursor.moveToNext();
}
}
}
}


//Hide the drop down. Not the most elegent solution but it is the only way I could hide/dismiss the drop down
mSpinnerDropDown = view.getRootView();
mSpinnerDropDownShowing = false;
mSpinnerDropDown.setVisibility(View.GONE);
}
};


private class MyCursorAdapter extends CursorAdapter {


private final int DISPLACEMENT = 1;
private final int DEFAULT_ITEM_ID = Integer.MAX_VALUE;


private Activity mActivity;


public MyCursorAdapter(Activity activity) {
super(activity, null, false);
mActivity = activity;
}


//When loading the regular views, inject the defualt item
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(position == 0){
if(convertView == null){
convertView = mActivity.getLayoutInflater().inflate(R.layout.list_item_widget, parent, false);
}
return getDefaultItem(convertView);
}
return super.getView(position - DISPLACEMENT, convertView, parent);
}


//When loading the drop down views, set the onClickListener for each view
@Override
public View getDropDownView(int position, View convertView, ViewGroup parent){
View view = super.getDropDownView(position, convertView, parent);
view.setOnClickListener(spinnerItemClick);
return view;
}


//The special default item that is being injected
private View getDefaultItem(View convertView){
TextView text = (TextView) convertView.findViewById(android.R.id.text1);
text.setText(SPINNER_INIT_VALUE);
return convertView;
}


@Override
public long getItemId(int position) {
if (position == 0) {
return DEFAULT_ITEM_ID;
}
return super.getItemId(position - DISPLACEMENT);
}


@Override
public boolean isEnabled(int position) {
return position == 0 ? true : super.isEnabled(position - DISPLACEMENT);
}


@Override
public int getViewTypeCount() {
return super.getViewTypeCount() + DISPLACEMENT;
}


@Override
public int getItemViewType(int position) {
if (position == 0) {
return super.getViewTypeCount();
}


return super.getItemViewType(position - DISPLACEMENT);
}


@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
return mActivity.getLayoutInflater().inflate(R.layout.list_item_widget, parent, false);
}


@Override
public void bindView(View view, Context context, Cursor cursor){


if(cursor.isAfterLast()){
return;
}


TextView text = (TextView) view.findViewById(android.R.id.text1);
String WidgetName = cursor.getString(WidgetQuery.WIDGET_NAME);
text.setText(WidgetName);
}
}
}

小开

你可以把它变成一个文本视图，并使用这个:

android:style="@android:style/Widget.DeviceDefault.Light.Spinner"

然后定义android:text属性。

小开

我通过使用按钮而不是旋转器来处理这个问题。# EYZ0

在项目中，我同时显示旋转器和按钮，以显示它们确实看起来相同。除了按钮，你可以将初始文本设置为任何你想要的。

下面是活动的样子:

package com.stevebergamini.spinnerbutton;


import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Spinner;


public class MainActivity extends Activity {


Spinner spinner1;
Button button1;
AlertDialog ad;
String[] countries;


int selected = -1;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);


spinner1 = (Spinner) findViewById(R.id.spinner1);
button1 = (Button) findViewById(R.id.button1);


countries = getResources().getStringArray(R.array.country_names);


//  You can also use an adapter for the allert dialog if you'd like
//  ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_dropdown_item, countries);


ad = new AlertDialog.Builder(MainActivity.this).setSingleChoiceItems(countries, selected,
new  DialogInterface.OnClickListener() {


@Override
public void onClick(DialogInterface dialog, int which) {
button1.setText(countries[which]);
selected = which;
ad.dismiss();


}}).setTitle(R.string.select_country).create();




button1.setOnClickListener( new OnClickListener(){


@Override
public void onClick(View v) {
ad.getListView().setSelection(selected);
ad.show();
}});


}


}

是的，我意识到这是依赖于应用的主题和外观将略有不同，如果使用Theme. holo。但是，如果您使用的是遗留主题之一，如Theme。黑色，你可以开始了。

小开

似乎是一个平庸的解决方案，但我通常把简单的TextView在纺纱器的前面。整个Xml是这样的。(嘿，伙计们，别朝我开枪，我知道你们有些人不喜欢这种婚姻):

<FrameLayout
android:id="@+id/selectTypesLinear"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >


<Spinner
android:id="@+id/spinnerExercises"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:entries="@array/exercise_spinner_entries"
android:prompt="@string/exercise_spinner_prompt"
/>
<TextView
android:id="@+id/spinnerSelectText"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="Hey! Select this guy!"
android:gravity="center"
android:background="#FF000000" />




</FrameLayout>

然后我隐藏TextView时，一个项目被选中。显然，TextView的背景颜色应该与旋转器相同。适用于Android 4.0。不知道旧版本。

是的。因为Spinner在开始时调用setOnItemSelectedListener，隐藏textview可能有点棘手，但可以这样做:

    Boolean controlTouched;


exerciseSpinner.setOnTouchListener(new OnTouchListener() {




@Override
public boolean onTouch(View v, MotionEvent event) {
controlTouched = true; // I touched it but but not yet selected an Item.
return false;
}


});
exerciseSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {


@Override
public void onItemSelected(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
if (controlTouched) { // Are you sure that I touched it with my fingers and not someone else  ?
spinnerSelText.setVisibility(View.GONE);
}
}


@Override
public void onNothingSelected(AdapterView<?> arg0) {
}


});

小开

如果你正面临这个问题当你的项目从数据库游标填充，

我在这中找到的最简单的解决方案，所以回答:

在游标适配器查询中使用UNION并将id= -1的附加项添加到查询结果中，而不真正将其添加到DB中:

喜欢的东西:

db.rawQuery("SELECT iWorkerId as _id, nvLastName as name  FROM  Worker
w  UNION  SELECT -1 as _id , '' as name",null);

如果选择的项目是-1，那么它是默认值。否则

小开

没有默认的API来设置微调提示。为了添加它，我们需要一个小的解决方案，而不是安全反射实现

List<Object> objects = new ArrayList<Object>();
objects.add(firstItem);
objects.add(secondItem);
// add hint as last item
objects.add(hint);


HintAdapter adapter = new HintAdapter(context, objects, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);


Spinner spinnerFilmType = (Spinner) findViewById(R.id.spinner);
spinner.setAdapter(adapter);


// show hint
spinner.setSelection(adapter.getCount());

适配器来源:

public class HintAdapter
extends ArrayAdapter<Objects> {


public HintAdapter(Context theContext, List<Object> objects) {
super(theContext, android.R.id.text1, android.R.id.text1, objects);
}


public HintAdapter(Context theContext, List<Object> objects, int theLayoutResId) {
super(theContext, theLayoutResId, android.R.id.text1, objects);
}


@Override
public int getCount() {
// don't display last item. It is used as hint.
int count = super.getCount();
return count > 0 ? count - 1 : count;
}
}

原始来源 .

小开

对我来说，它是这样工作的。有改进，只改变文本在某些选项，而不是全部。

首先，我采用旋转器的名称并创建带有自定义视图的arrayadapter，但现在这并不重要，关键是覆盖getView，并在内部更改你需要更改的值。在我的情况下只有第一个，其余的我离开原来的

public void rellenarSpinnerCompeticiones(){
spinnerArrayCompeticiones = new ArrayList<String>();
for(Competicion c: ((Controlador)getApplication()).getCompeticiones()){
spinnerArrayCompeticiones.add(c.getNombre());
}
//ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this,R.layout.spinner_item_competicion,spinnerArrayCompeticiones);
ArrayAdapter<String> spinnerArrayAdapter = new ArrayAdapter<String>(this, R.layout.spinner_item_competicion, spinnerArrayCompeticiones){
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
final View v = vi.inflate(R.layout.spinner_item_competicion, null);
final TextView t = (TextView)v.findViewById(R.id.tvCompeticion);
if(spinnerCompeticion.getSelectedItemPosition()>0){
t.setText(spinnerArrayCompeticiones.get(spinnerCompeticion.getSelectedItemPosition()));
}else{
t.setText("Competiciones");
}
return v;
}
};
spinnerArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinnerCompeticion.setAdapter(spinnerArrayAdapter);
}

小开

此代码已经过测试，在Android 4.4上工作

enter image description here

Spinner spinner = (Spinner) activity.findViewById(R.id.spinner);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(activity, android.R.layout.simple_spinner_dropdown_item) {


@Override
public View getView(int position, View convertView, ViewGroup parent) {


View v = super.getView(position, convertView, parent);
if (position == getCount()) {
((TextView)v.findViewById(android.R.id.text1)).setText("");
((TextView)v.findViewById(android.R.id.text1)).setHint(getItem(getCount())); //"Hint to be displayed"
}


return v;
}


@Override
public int getCount() {
return super.getCount()-1; // you dont display last item. It is used as hint.
}


};


adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
adapter.add("Daily");
adapter.add("Two Days");
adapter.add("Weekly");
adapter.add("Monthly");
adapter.add("Three Months");
adapter.add("HINT_TEXT_HERE"); //This is the text that will be displayed as hint.




spinner.setAdapter(adapter);
spinner.setSelection(adapter.getCount()); //set the hint the default selection so it appears on launch.
spinner.setOnItemSelectedListener(this);

小开

我找到了很多很好的解决方案。大多数是通过在适配器的末尾添加一个项来工作的，并且不在下拉列表中显示最后一个项。对我来说最大的问题是旋转器下拉列表将从列表的底部开始。所以用户第一次触摸转轮后，看到的是最后一个项目而不是第一个项目(以防有很多项目要显示)

所以我把提示项放在列表的开头。并在下拉列表中隐藏第一项。

private void loadSpinner(){


HintArrayAdapter hintAdapter = new HintArrayAdapter<String>(context, 0);


hintAdapter.add("Hint to be displayed");
hintAdapter.add("Item 1");
hintAdapter.add("Item 2");
.
.
hintAdapter.add("Item 30");


spinner1.setAdapter(hintAdapter);


//spinner1.setSelection(0); //display hint. Actually you can ignore it, because the default is already 0
//spinner1.setSelection(0, false); //use this if don't want to onItemClick called for the hint


spinner1.setOnItemSelectedListener(yourListener);
}


private class HintArrayAdapter<T> extends ArrayAdapter<T> {


Context mContext;


public HintArrayAdapter(Context context, int resource) {
super(context, resource);
this.mContext = context
}


@Override
public View getView(int position, View convertView, ViewGroup parent) {


LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(android.R.layout.simple_spinner_item, parent, false);
TextView texview = (TextView) view.findViewById(android.R.id.text1);


if(position == 0) {
texview.setText("");
texview.setHint(getItem(position).toString()); //"Hint to be displayed"
} else {
texview.setText(getItem(position).toString());
}


return view;
}


@Override
public View getDropDownView(int position, View convertView, ViewGroup parent) {


LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
View view;


if(position == 0){
view = inflater.inflate(R.layout.spinner_hint_list_item_layout, parent, false); // Hide first row
} else {
view = inflater.inflate(android.R.layout.simple_spinner_dropdown_item, parent, false);
TextView texview = (TextView) view.findViewById(android.R.id.text1);
texview.setText(getItem(position).toString());
}


return view;
}
}

在@Override getDropDownView()中设置下面的布局，当position为0时，隐藏第一个提示行。

R.layout.spinner_hint_list_item_layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content" >


</LinearLayout>

小开

private boolean isFirst = true;
private void setAdapter() {
final ArrayList<String> spinnerArray = new ArrayList<String>();
spinnerArray.add("Select your option");
spinnerArray.add("Option 1");
spinnerArray.add("Option 2");
spin.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
TextView tv = (TextView)selectedItemView;
String res = tv.getText().toString().trim();
if (res.equals("Option 1")) {
//do Something
} else if (res.equals("Option 2")) {
//do Something else
}
}


@Override
public void onNothingSelected(AdapterView<?> parentView) { }


});
            

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.my_spinner_style,spinnerArray) {
public View getView(int position, View convertView, ViewGroup parent) {
View v = super.getView(position, convertView, parent);
int height = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 25, getResources().getDisplayMetrics());
((TextView) v).setTypeface(tf2);
((TextView) v).getLayoutParams().height = height;
((TextView) v).setGravity(Gravity.CENTER);
((TextView) v).setTextSize(TypedValue.COMPLEX_UNIT_SP, 19);
((TextView) v).setTextColor(Color.WHITE);
return v;
}


public View getDropDownView(int position, View convertView,
ViewGroup parent) {
if (isFirst) {
isFirst = false;
spinnerArray.remove(0);
}
View v = super.getDropDownView(position, convertView, parent);
((TextView) v).setTextColor(Color.argb(255, 70, 70, 70));
((TextView) v).setTypeface(tf2);
((TextView) v).setGravity(Gravity.CENTER);
return v;
}
};
spin.setAdapter(adapter);
}

小开

 ArrayList<String> sizes = new ArrayList<>();


spinner = (Spinner) findViewById(R.id.spinner_size);


if (sizes != null && !sizes.isEmpty()) {


//SORT ArrayList If You Want Data in ASC or DSC Order


sizes.add("28");
sizes.add("29");
sizes.add("31");


sizes.add("Choose Size"); //adding String at the end of ArrayList
Collections.reverse(sizes); //Last Item Will Be Shown As A Spinner Title


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

简单地使用数组列表。add("Your Data")方法在数组列表的末尾添加项，然后使用Collection.reverse(arrayList)反转它，以便标题是Spinner中的第一个项。还可以在最后添加数据之前对项目进行排序。 enter image description here

小开

参考上述答案之一:https://stackoverflow.com/a/23005376/1312796

我添加了我的代码来修复一个小错误。哪里没有数据检索..如何显示提示文本..!

这是我的诀窍……我觉得挺好用的。！

试着把你的旋转器在一个relative_layout和对齐的Textview与你的旋转器和发挥Textview的可见性(SHOW/HIDE)每当旋转器的适配器加载或空..像这样:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="20dp"
android:background="#ededed"
android:orientation="vertical">






<TextView
android:id="@+id/txt_prompt_from"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:textColor="@color/gray"
android:textSize="16sp"
android:layout_alignStart="@+id/sp_from"
android:text="From"
android:visibility="gone"/>


<Spinner
android:id="@+id/sp_from"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
/>

代码如下:

  txt__from = (TextView) rootView.findViewById(R.id.txt_prompt_from);

在转轮适配器加载并为空前后调用此方法。

setPromptTextViewVisibility (); //True or fales


public void setPromptTextViewVisibility (boolean visible )
{
if (visible)
{
txt_from.setVisibility(View.VISIBLE);
}
else
{
txt_from.setVisibility(View.INVISIBLE);
}


}

小开

考虑有N个项目要选择。

添加完这N个项目后，添加提示文本作为(N+1)个项目。

将所选项目设置为第N个位置[(N+1)个项目]。

在OnItemSelected Listener中，如果所选位置不是N，弹出最后一个项目并调用Adapter.notifyDataSetChanged()并将所选项目设置为所选位置。

就像这样:

    spinner.setItems("Daily", "One time", "Frequency"); // here "Frequency is the hint text"
spinner.setSelectedIndex(2);


spinner.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(Spinner view, int position, long id, Object item) {
if (position != 2) {
view.setItems("Daily", "One time");
view.setSelectedIndex(position);
}else {
// This item is not a valid selection
}
}
});

小开

String[] listAges = getResources().getStringArray(R.array.ages);


// Creating adapter for spinner
ArrayAdapter<String> dataAdapter =
new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, listAges);


// Drop down layout style - list view with radio button
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);


// attaching data adapter to spinner
spinner_age.getBackground().setColorFilter(ContextCompat.getColor(this, R.color.spinner_icon), PorterDuff.Mode.SRC_ATOP);
spinner_age.setAdapter(dataAdapter);
spinner_age.setSelection(0);
spinner_age.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String item = parent.getItemAtPosition(position).toString();


if(position > 0){
// get spinner value
Toast.makeText(parent.getContext(), "Age..." + item, Toast.LENGTH_SHORT).show();
}else{
// show toast select gender
Toast.makeText(parent.getContext(), "none" + item, Toast.LENGTH_SHORT).show();
}
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});

小开

对于那些使用Xamarin的人，下面是与上面aaronvargas的答案相当的c#版本。

using Android.Content;
using Android.Database;
using Android.Views;
using Android.Widget;
using Java.Lang;


namespace MyNamespace.Droid
{
public class NothingSelectedSpinnerAdapter : BaseAdapter, ISpinnerAdapter, IListAdapter
{
protected static readonly int EXTRA = 1;
protected ISpinnerAdapter adapter;
protected Context context;
protected int nothingSelectedLayout;
protected int nothingSelectedDropdownLayout;
protected LayoutInflater layoutInflater;


public NothingSelectedSpinnerAdapter(ISpinnerAdapter spinnerAdapter, int nothingSelectedLayout, Context context) : this(spinnerAdapter, nothingSelectedLayout, -1, context)
{
}


public NothingSelectedSpinnerAdapter(ISpinnerAdapter spinnerAdapter, int nothingSelectedLayout, int nothingSelectedDropdownLayout, Context context)
{
this.adapter = spinnerAdapter;
this.context = context;
this.nothingSelectedLayout = nothingSelectedLayout;
this.nothingSelectedDropdownLayout = nothingSelectedDropdownLayout;
layoutInflater = LayoutInflater.From(context);
}


protected View GetNothingSelectedView(ViewGroup parent)
{
return layoutInflater.Inflate(nothingSelectedLayout, parent, false);
}


protected View GetNothingSelectedDropdownView(ViewGroup parent)
{
return layoutInflater.Inflate(nothingSelectedDropdownLayout, parent, false);
}


public override Object GetItem(int position)
{
return position == 0 ? null : adapter.GetItem(position - EXTRA);
}


public override long GetItemId(int position)
{
return position >= EXTRA ? adapter.GetItemId(position - EXTRA) : position - EXTRA;
}


public override 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);
}


// Could re-use the convertView if possible.
return this.adapter.GetView(position - EXTRA, null, parent);
}


public override int Count
{
get
{
int count = this.adapter.Count;
return count == 0 ? 0 : count + EXTRA;
}
}


public override 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);
}


public override int GetItemViewType(int position)
{
return 0;
}


public override int ViewTypeCount => 1;


public override bool HasStableIds => this.adapter.HasStableIds;


public override bool IsEmpty => this.adapter.IsEmpty;


public override void RegisterDataSetObserver(DataSetObserver observer)
{
adapter.RegisterDataSetObserver(observer);
}


public override void UnregisterDataSetObserver(DataSetObserver observer)
{
adapter.UnregisterDataSetObserver(observer);
}


public override bool AreAllItemsEnabled()
{
return false;
}


public override bool IsEnabled(int position)
{
return position > 0;
}
}
}

小开

这里有很多答案，但我很惊讶没有人提出一个简单的解决方案:在旋转器的顶部放置一个TextView。在TextView上设置一个点击监听器，它隐藏了显示Spinner的TextView，并调用spiner . performclick()。

小开

我还通过使用以下代码解决了这个问题。假设你有一个项目列表。

ArrayList<Item> itemsArrayList = new ArrayList<Item>();
Item item1 = new Item();
item1.setId(1);
item1.setData("First Element");
Item item2 = new Item();
item2.setId(2);
Item2.setData("Second Element");
itemsArrayList.add(item1);
itemsArrayList.add(item2);

现在我们必须向spinner提供字符串，因为spinner无法理解对象。因此，我们将创建一个包含如下字符串项的新数组列表->

ArrayList<String> itemStringArrayList = new ArrayList<String>();
for(Item item : itemsArrayList) {
itemStringArrayList.add(item.getData());
}

现在我们有了带有两个字符串项的itemStringArrayList数组列表。我们必须将“Select Item”文本显示为第一项。所以我们必须在itemStringArrayList中插入一个新字符串。

itemStringArrayList.add("Select Item");

现在我们有了一个数组列表itemsArrayList，我们想在下拉列表中显示两个元素。但这里的条件是…如果我们不选择任何东西，那么Select Item应该作为第一个元素出现，这将不会被启用。

我们可以像这样实现这个功能。如果你需要将数组列表项加载到android spinner。所以你必须使用一些适配器。所以这里我将使用ArrayAdapter。我们也可以使用定制适配器。

ArrayAdapter<String> itemsArrayAdapter = new ArrayAdapter<String>(getApplicationContext(), R.layout.spinner_item, itemsArrayList){
@Override
public boolean isEnabled(int position) {
if(position == 0)
{
return false;
}
else
{
return true;
}
}


@Override
public View getDropDownView(int position, View convertView,
ViewGroup parent) {
View view = super.getDropDownView(position, convertView, parent);
TextView tv = (TextView) view;
if(position == 0){
// Set the hint text color gray
tv.setTextColor(Color.GRAY);
}
else {
tv.setTextColor(Color.BLACK);
}
return view;
}
};


itemsArrayAdapter.setDropDownViewResource(R.layout.spinner_item);
your_spinner_name.setAdapter(itemsArrayAdapter);

在这个代码中。我们使用自定义的旋转器布局，即R.layout.spinner_item。这是一个简单的文本视图

<?xml version="1.0" encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:textStyle="italic"
android:fontFamily="sans-serif-medium"
/>

我们需要禁用转轮中的第一个文本。对于0号位置，我们禁用了文本。颜色也可以通过覆盖getDropDownView方法来设置。这样我们就能得到预期的转轮。

小开

我昨天遇到了同样的问题，不想向ArrayAdapter添加隐藏项或使用反射，这工作得很好，但有点脏。

在阅读了许多帖子和尝试之后，我通过扩展ArrayAdapter和覆盖getView方法找到了一个解决方案。

import android.content.Context;
import android.support.annotation.NonNull;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;


/**
* A SpinnerAdapter which does not show the value of the initial selection initially,
* but an initialText.
* To use the spinner with initial selection instead call notifyDataSetChanged().
*/
public class SpinnerAdapterWithInitialText<T> extends ArrayAdapter<T> {


private Context context;
private int resource;


private boolean initialTextWasShown = false;
private String initialText = "Please select";


/**
* Constructor
*
* @param context The current context.
* @param resource The resource ID for a layout file containing a TextView to use when
*                 instantiating views.
* @param objects The objects to represent in the ListView.
*/
public SpinnerAdapterWithInitialText(@NonNull Context context, int resource, @NonNull T[] objects) {
super(context, resource, objects);
this.context = context;
this.resource = resource;
}


/**
* Returns whether the user has selected a spinner item, or if still the initial text is shown.
* @param spinner The spinner the SpinnerAdapterWithInitialText is assigned to.
* @return true if the user has selected a spinner item, false if not.
*/
public boolean selectionMade(Spinner spinner) {
return !((TextView)spinner.getSelectedView()).getText().toString().equals(initialText);
}


/**
* Returns a TextView with the initialText the first time getView is called.
* So the Spinner has an initialText which does not represent the selected item.
* To use the spinner with initial selection instead call notifyDataSetChanged(),
* after assigning the SpinnerAdapterWithInitialText.
*/
@Override
public View getView(int position, View recycle, ViewGroup container) {
if(initialTextWasShown) {
return super.getView(position, recycle, container);
} else {
initialTextWasShown = true;
LayoutInflater inflater = LayoutInflater.from(context);
final View view = inflater.inflate(resource, container, false);


((TextView) view).setText(initialText);


return view;
}
}
}

Android在初始化Spinner时所做的，是在为T[] objects中的所有项目调用getView之前为所选项目调用getView。 SpinnerAdapterWithInitialText在第一次调用时返回TextView和initialText。所有其他时候，它调用super.getView，这是ArrayAdapter的getView方法，如果你正常使用Spinner，则会调用ArrayAdapter

要确定用户是否选择了一个微调项，或者微调项是否仍然显示initialText，请调用selectionMade并移交适配器分配给的微调项。

小开

public AdapterView.OnItemSelectedListener instructorSpinnerListener = new AdapterView.OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView << ? > adapterView, View view, int i, long l) {
String selectedInstructorName = adapterView.getItemAtPosition(i).toString();
if (selectedInstructorName.equals("[Select Instructor]")) {
instructorSpinnerAdapter.clear();
for (Offering offering: allOfferingsList)
instructorSpinnerAdapter.add(offering);
} else {
instructorSpinnerAdapter.clear();
}
}


@Override
public void onNothingSelected(AdapterView<< ? > adapterView) {
adapterView.setSelection(0);


// Toast.makeText(getApplicationContext(), "Why?", Toast.LENGTH_SHORT).show();
}
};

小开

此外，还有一个简单的技巧来显示默认值:

您可以在列表中添加一个默认值，然后使用list.addAll(yourCollection);添加所有集合

下面是可操作的示例代码:

List<FuelName> fuelList = new ArrayList<FuelName>();
fuelList.add(new FuelName(0,"Select One"));
fuelList.addAll(response.body());
ArrayAdapter adapter = new ArrayAdapter<>(getActivity(), android.R.layout.simple_spinner_item, fuelList);
//fuelName.setPrompt("Select Fuel");
fuelName.setAdapter(adapter);

小开

最好的解决方案，我发现这实际上不是使用一个纺纱机，而是一个AutoCompleteTextView。它基本上是一个带有附加Spinner的EditText，可以在你输入时显示建议-但是，通过正确的配置，它可以完全按照OP的要求进行操作。

XML:

<com.google.android.material.textfield.TextInputLayout
android:id="@+id/item"
android:layout_width="match_parent"
android:layout_height="wrap_content">


<androidx.appcompat.widget.AppCompatAutoCompleteTextView
android:id="@+id/input"
android:hint="Select one"
style="@style/AutoCompleteTextViewDropDown"/>
</com.google.android.material.textfield.TextInputLayout>

风格:

<style name="AutoCompleteTextViewDropDown">
<item name="android:clickable">false</item>
<item name="android:cursorVisible">false</item>
<item name="android:focusable">false</item>
<item name="android:focusableInTouchMode">false</item>
<item name="android:layout_width">match_parent</item>
<item name="android:layout_height">wrap_content</item>
</style>

至于适配器，使用基本的ArrayAdapter或扩展它来创建自己的适配器，但不需要在适配器方面进行额外的定制。在AutoCompleteTextView上设置适配器。

小开

看到答案与轻量级和高可定制的库:

https://stackoverflow.com/a/73085435/6694920 < a href = " https://stackoverflow.com/a/73085435/6694920 " > < / >

<com.innowisegroup.hintedspinner.HintedSpinner
android:id="@+id/hintedSpinner"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginHorizontal="20dp"
app:hintTextSize="24sp"
app:hintTextColor="@color/red"
app:hint="Custom hint"
app:withDivider="true"
app:dividerColor="@color/dark_green"
app:arrowDrawable="@drawable/example_arrow_4"
app:arrowTint="@color/colorAccent"
app:popupBackground="@color/light_blue"
app:items="@array/text" />

< p >倒塌转轮: # EYZ0 < / p >

扩大转轮: