我已经在C＃中使用Xamarin实现了这个custom DialogPreference但是我在将其添加到我的xml文件时遇到了问题。
namespace Client.Android
{
public class TimePreference : DialogPreference
{
private int lastHour = 0;
private int lastMinute = 0;
private TimePicker picker = null;
public static int GetHour(string time)
{
string[] pieces = time.Split (':');
return Convert.ToInt32 (pieces [0]);
}
public static int GetMinute(string time)
{
string[] pieces = time.Split (':');
return Convert.ToInt32 (pieces [1]);
}
public TimePreference(Context context, IAttributeSet attSet) : base(context, attSet)
{
SetPositiveButtonText (Resource.String.time_preference_set);
SetNegativeButtonText (Resource.String.time_preference_cancel);
}
protected override View OnCreateDialogView ()
{
picker = new TimePicker (Context);
return picker;
}
protected override void OnBindDialogView (View view)
{
base.OnBindDialogView (view);
picker.CurrentHour = (Java.Lang.Integer) lastHour;
picker.CurrentMinute = (Java.Lang.Integer) lastMinute;
}
protected override void OnDialogClosed (bool positiveResult)
{
base.OnDialogClosed (positiveResult);
if (positiveResult) {
lastHour = (int) picker.CurrentHour;
lastMinute = (int) picker.CurrentMinute;
string time = lastHour + ":" + lastMinute;
if (CallChangeListener (time)) {
PersistString (time);
}
}
}
protected override Java.Lang.Object OnGetDefaultValue (TypedArray a, int index)
{
return a.GetString (index);
}
protected override void OnSetInitialValue (bool restorePersistedValue, Java.Lang.Object defaultValue)
{
string time = string.Empty;
if (restorePersistedValue) {
if (defaultValue == null) {
time = GetPersistedString ("00:00");
} else {
time = GetPersistedString (defaultValue.ToString ());
}
} else {
time = defaultValue.ToString ();
}
lastHour = GetHour (time);
lastMinute = GetMinute (time);
}
}
}
我的项目名称/默认命名空间是“Client.Android”，我尝试将其添加到我的xml文件中，如下所示：
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
<PreferenceCategory android:title="@string/pref_foo" >
...
<Client.Android.TimePreference
android:title="@string/pref_bar"
android:key="@string/prefkey_bar"
android:defaultValue="12:00" />
...
</PreferenceCategory>
</PreferenceScreen>
但我在AddPreferencesFromResource(Resource.Xml.settings);方法的OnCreate上收到以下异常：
Android.Views.InflateException: Binary XML file line #32: Error inflating class Client.Android.TimePreference
at Android.Runtime.JNIEnv.CallNonvirtualVoidMethod (intptr,intptr,intptr,Android.Runtime.JValue[]) [0x00084] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.12-series/7f0e3d3c/source/monodroid/src/Mono.Android/src/Runtime/JNIEnv.g.cs:895
at Android.Preferences.PreferenceActivity.AddPreferencesFromResource (int) [0x00070] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.12-series/7f0e3d3c/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.Preferences.PreferenceActivity.cs:729
at Client.Android.SettingsActivity.OnCreate (Android.OS.Bundle) [0x00015] in c:\pushtotalk\Client.Android\SettingsActivity.cs:45
at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (intptr,intptr,intptr) [0x00011] in /Users/builder/data/lanes/monodroid-mlion-monodroid-4.12-series/7f0e3d3c/source/monodroid/src/Mono.Android/platforms/android-19/src/generated/Android.App.Activity.cs:2178
at at (wrapper dynamic-method) object.7c9f4d4d-9496-4803-b019-cd453beeee8b (intptr,intptr,intptr) <IL 0x00017, 0x00043>
at --- End of managed exception stack trace ---
at android.view.InflateException: Binary XML file line #32: Error inflating class Client.Android.TimePreference
at at android.preference.GenericInflater.createItemFromTag(GenericInflater.java:441)
at at android.preference.GenericInflater.rInflate(GenericInflater.java:481)
at at android.preference.GenericInflater.rInflate(GenericInflater.java:493)
at at android.preference.GenericInflater.inflate(GenericInflater.java:326)
at at android.preference.GenericInflater.inflate(GenericInflater.java:263)
at at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:272)
at at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:1472)
at at client.android.SettingsActivity.n_onCreate(Native Method)
at at client.android.SettingsActivity.onCreate(SettingsActivity.java:32)
at at android.app.Activity.performCreate(Activity.java:5231)
at at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
at at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
at at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
at at android.app.ActivityThread.access$800(ActivityThread.java:135)
at at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at at android.os.Handler.dispatchMessage(Handler.java:102)
at at android.os.Looper.loop(Looper.java:136)
at at android.app.ActivityThread.main(ActivityThread.java:5017)
at at java.lang.reflect.Method.invokeNative(Native Method)
at at java.lang.reflect.Method.invoke(Method.java:515)
at at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at at dalvik.system.NativeStart.main(Native Method)
at Caused by: java.lang.ClassNotFoundException: Didn't find class "Client.Android.TimePreference" on path: DexPathList[[zip file "/data/app/Client.Android-1.apk"],nativeLibraryDirectories=[/data/app-lib/Client.Android-1, /vendor/lib, /system/lib]]
at at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
at at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
at at android.preference.GenericInflater.createItem(GenericInflater.java:375)
at at android.preference.GenericInflater.createItemFromTag(GenericInflater.java:430)
at ... 22 more
答案 0 :(得分：4)
这些是default attributes可用的（您还可以通过展开android docs for DialogPreference中的Inherited XML Attributes块来查看继承的属性）：
android:dialogIcon - The icon for the dialog.
android:dialogLayout - A layout to be used as the content View for the dialog.
android:dialogMessage - The message in the dialog.
android:dialogTitle - The title in the dialog.
android:negativeButtonText - The negative button text for the dialog.
android:positiveButtonText - The positive button text for the dialog.
因此，为了使用您自己的属性，您需要创建自己的Resource文件，为Stylable定义DialogPreference，如：
<强>资源\值\ MyTimePreferenceAttrs.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="MyTimePreference">
<attr name="defaultValue" format="string"/>
</declare-styleable>
</resources>
然后，在您创建TimePreference视图的AXML布局中，您需要添加命名空间以便可以解析它们：
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:my="http://schemas.android.com/apk/res-auto" >
<PreferenceCategory android:title="@string/pref_foo" >
...
<Client.Android.TimePreference
my:defaultValue="12:00" />
...
</PreferenceCategory>
</PreferenceScreen>
然后在TimePreference的构造函数中，您可以使用以下内容获取值：
var ta = context.ObtainStyledAttributes(attrs, Resource.Styleable.MyTimePreference);
var defaultValue = ta.GetString(Resource.Styleable.MyTimePreference_defaultValue);
ta.Recycle();
您也可能在XML布局中使用大写命名空间时遇到问题。但是，类名保持大写，因此：
<client.android.TimePreference
...