如何制作一个初始文本为“选择一个”的 Android Spinner?
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22-08-2019 - |
题
我想使用一个最初(当用户尚未做出选择时)显示文本“选择一个”的微调器。当用户单击微调器时,将显示项目列表,并且用户选择其中一个选项。用户做出选择后,所选项目将显示在微调器中,而不是“选择一个”。
我有以下代码来创建 Spinner:
String[] items = new String[] {"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);
使用此代码,最初会显示项目“One”。我可以只向项目添加一个新项目“选择一个”,但是“选择一个”也会作为第一项显示在下拉列表中,这不是我想要的。
我该如何解决这个问题?
解决方案
下面是覆盖Spinner
视图一个通用的解决方案。它覆盖setAdapter()
到初始位置设置为-1,和代理所提供的SpinnerAdapter
以显示位置的提示字符串小于0。
此已经关于机器人1.5 4.2通过了测试,但买方小心!由于这种解决方案依赖于反射调用私有AdapterView.setNextSelectedPositionInt()
和AdapterView.setSelectedPositionInt()
,它不能保证在未来的操作系统的更新工作。这很可能是会,但它绝不是一种保障手段。
通常我不会容忍这样的事情,但这个问题已经被问足够的时间,好像,我想我会后我的解决方案不够合理要求。
/**
* 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);
}
}
}
其他提示
你可以做的是一个呈现装点你SpinnerAdapter
“选择选项...”查看最初的微调与选定任何显示。
下面是Android 2.3测试一个工作示例,和4.0(它使用没有在兼容性库,所以它应该是精细的一段时间)由于它是一个装饰,应该很容易改造现有的代码并能正常工作与CursorLoader
s也。 (交换光标上当然包裹cursorAdapter
...)
有是一个Android错误,使得严厉这一点重新使用的景色。 (所以,你必须使用setTag
或别的东西,以确保您convertView
是正确的。)的微调不支持多视图类型
代码的注释:2层的构造
这允许你使用一个标准的提示或定义为第一行自己“什么也没有选择”,或两者,或根本没有。 (注意:某些主题示出了用于微调,而不是一个对话一个下拉的下拉通常不显示提示)
您定义布局“看”等的提示,例如,变灰...
使用标准提示(注意没有被选中):
或者与提示和东西动态(可有没有提示也):
<强>在上面的例子中使用强>
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));
<强> contact_spinner_row_nothing_selected.xml 强>
<?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...]" />
<强> NothingSelectedSpinnerAdapter.java 强>
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.
}
}
我最终使用一个Button
代替。虽然Button
不是Spinner
,行为是容易定制。
首先创建适配器照例:
String[] items = new String[] {"One", "Two", "Three"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_spinner_dropdown_item, items);
请注意,我现在用的是simple_spinner_dropdown_item
作为布局ID。这将有助于创造的警告对话框中,当创建一个更好看。
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();
}
这就是它!
我知道这个问题有很多答案,但我发现这样做的最简单和最简单的方法。
<强> 该溶液是无关的API级的,它将所有的API级的作品
思想是设置旋转器作为默认one..ie的最后一个项目
spinner.setSelection(lastIndex);//index starts from 0.so if spinner has 5 item the lastIndex is 4
在过去的指标项目应该是你喜欢“选择国家”
微调的标题和在填充离心器由one.i.e减少项目的计 //计数从1开始的总项。
@Override
public int getCount() {
// don't display last item. It is used as hint.
int count = super.getCount();
return count > 0 ? count - 1 : count;
}
所以,你的代码流会是这样
List<String> objects = new ArrayList<String>();
objects.add("India");
objects.add("Pakistan");
objects.add("China");
// add hint as last item
objects.add("Select Country");
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());
HintAdapter.java
public class HintAdapter extends ArrayAdapter<Objects> {
public HintAdapter(Context theContext, List<Object> objects, int theLayoutResId) {
super(theContext, theLayoutResId, 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;
}
}
微调名称
微调档案
此代码已被测试并适用于Android 4.4
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);
我发现此解决方案:
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) {
}
});
只要改变阵列[0]与在onItemSelected“选择一项”,然后,将其重命名为“一”。
不是一个优雅的解决方案,但它的工作原理:d
没有缺省API来设置提示上微调。要添加它,我们需要一个小的解决办法有,并非安全性反射实施
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;
}
}
很多答案在这里,但我很惊讶,没有一个人提出了一个简单的解决方案:将在微调的顶部一个TextView。设置在其上隐藏的TextView示出了微调TextView的一个点击监听,并调用spinner.performClick()。
我得到微调的同样的问题,用一个空的选择,以及我发现了一个更好的解决方案。看看这个简单的代码。
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);
下面spinneradapter为arrayadapter小定制。它看起来像这样:
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);
}
}
您可以将其更改为文本查看和使用这样的:
android:style="@android:style/Widget.DeviceDefault.Light.Spinner"
和然后定义android:text
属性。
XML文件:
<Spinner android:id="@+id/locationSpinner"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:prompt="@string/select_location" />
的活动:
private Spinner featuresSelection;
private ArrayAdapter<CharSequence> featuresAdapter;
private List<CharSequence> featuresList;
的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());
一些功能(添加的东西到适配器编程)>
featuresAdapter.add("some string");
现在你有一个空的微调,你可以写代码,如果空不打开对话框。或者,他们可以按回。但你也有一个功能或在运行时另一个列表填充它。
我试图像下面这样。以一个按钮,给click事件给它。通过改变按钮的背景,这似乎是一个旋转器。
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();
}
});
这是我的方式:
List<String> list = new ArrayList<String>();
list.add("string1");
list.add("string2");
list.add("string3");
list.add("[Select one]");
final int listsize = list.size() - 1;
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item, list) {
@Override
public int getCount() {
return(listsize); // Truncate the list
}
};
dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
mySpinner.setAdapter(dataAdapter);
mySpinner.setSelection(listsize); // Hidden item to appear in the spinner
查看 iosched 应用程序,了解将元素添加到列表顶部的通用解决方案。特别是,如果您使用的是 CursorAdapter,请查看 TracksAdapter.java 它扩展了该定义以提供“setHasAllItem”方法和关联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“选择一个”或您希望顶部项目显示的任何其他内容。
我在我的main.xml旋转器和其ID是@+id/spinner1
这是我在我的OnCreate函数写:
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) { }
});
它并不需要在类中的任何实施方式。
我发现这么多好的解决方案。大多数是通过将一个项目适配器一端的工作,也不要在下拉列表中显示的最后一个项目。 对我来说,最大的问题是微调下拉列表将从列表的底部开始。所以使用者看到最后项而不是第一项(在箱子有许多项目显示),触摸之后微调首次
所以我把提示项目到列表的开头。并隐藏在下拉列表中的第一项。
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(设置下面布局)时位置为0,以隐藏所述第一提示行。
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>
我觉得最简单的方法是在索引0创建一个虚拟物品说:“选择一个”,然后对储蓄也许检查选择不为0。
因此,这是我的最后一个例子“全”为一个按钮微调
在的 activity_my_form.xml 强>
<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>
在的的strings.xml 强>
<string name="selectAPlanet">Select planet…</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>
在的 MyFormActivity.java 强>
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,我获得的字体大小可配置无第一项可选择按钮喷丝!!! 由于HRJ
此外,有一个简单的窍门来显示默认:
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
这里样品可行代码:
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);
希望它恢复的复杂性。编码快乐!
当延伸SpinnerAdapter
,重写2 View
生产方法,getView(int, View, ViewGroup)
和getDropDownView(int, View, ViewGroup)
。第一个提供插入View
本身Spinner
;第二供应在下拉列表中View
(顾名思义)。可以重写getView(...)
使得直到项已被选择,则显示包含提示的TextView
;然后,当检测的项目被选择时,你改变它,以显示对应于该一个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;
}
}
//...
}
有关使用Xamarin那些,这里是C#等效于上面aaronvargas的答案。
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;
}
}
}
我还通过使用以下代码来解决这个问题。假设你正在例如,具有项目列表
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);
现在我们必须提供的字符串微调器,因为微调无法理解的对象。因此,我们将创建一个字符串项这样的一个新的数组列表 - >
ArrayList<String> itemStringArrayList = new ArrayList<String>();
for(Item item : itemsArrayList) {
itemStringArrayList.add(item.getData());
}
现在我们有两个字符串的项目itemStringArrayList
数组列表。我们必须要显示“选择项”文本作为第一个项目。所以我们要插入一个新的字符串到itemStringArrayList
。
itemStringArrayList.add("Select Item");
现在我们有一个数组列表itemsArrayList
,我们要显示在下拉两个元素。但这里的条件是......如果我们不选择任何内容,然后Select Item
应显示为,将不会启用第一个元素。
因此,我们可以实现这样的这一功能。如果您需要数组列表项加载到Android的微调。所以,你将不得不使用一些适配器。所以在这里我将使用ArrayAdapter
。我们可以使用自定义适配器了。
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);
在这里,在该代码。我们使用的是定制的微调布局,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"
/>
我们需要禁用微调的第一个文本。所以对于位置0,我们禁用的文本。而且颜色也可以通过overiding getDropDownView方法设置。所以这样我们就会得到预期的微调。
我只是用用单选按钮RadioGroup中,如果你只有三个选择,你可以让他们所有选中的第一位。
先前提交的答案都不果然奏效,我想解决这个问题的方式。对我来说,理想的解决方案将提供“选择一个”(或任何初始文本)时,首先显示的微调。当用户点击旋转器,初始文本不应下显示液滴的一部分。
要我的特定情况进一步复杂化,我的微调数据被未来形式,其经由LoaderManager回调加载的光标。
在相当大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);
}
}
}
我通过使用按钮,而不是微调处理这个问题。 我有示例项目向上GitHub上。
在项目中,我同时显示的微调和按钮来表明他们确实看起来完全相同。除按钮,你可以设置任何你想要的初始文本。
这里的活动是什么样子:
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();
}});
}
}
注意:是,我知道这是依赖于应用的主题和它的外表将是如果使用Theme.Holo略有不同。但是,如果您正在使用传统的主题,如Theme.Black之一,你是好去。
如果你正面临这个问题的当你的项目是从数据库光标填充
这在我发现最简单的解决这个,以便回答:
在你的光标适配器查询使用UNION 并与ID添加额外的项目= -1查询结果,而没有真正将其添加到数据库:
是这样的:
db.rawQuery(“选择iWorkerId如_id,nvLastName姓名FROM工人 瓦特UNION SELECT -1作为_id '' 姓名”,NULL);
如果选择的项目是-1,那么它的默认值。除此以外 它是从表中的记录。
似乎是一个陈腐解决方案,但我通常把只是一个TextView在所说的纺丝器的前部。整个XML看起来是这样的。 (嘿,伙计们,不要拍我,我知道一些你不喜欢这样的婚姻):
<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,我隐藏的TextView当被选择的项目。显然TextView的背景颜色应该是一样的微调。适用于Android 4.0。不知道在旧版本。
是。因为微调之初调用setOnItemSelectedListener,TextView的的藏身可能是一个有点棘手,但可以做这种方式:
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) {
}
});
对于我来说,它的工作是这样的。具有仅改变某些选项的文本,而不是在所有的改进。
首先,我采取微调的名称,并创建一个自定义视图一个ArrayAdapter,但没关系,现在的关键是覆盖getView和内改变u需要改变的值。在我的情况是只有第一个,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);
}
这里是一个简单的一个
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);
}