我已经扩展了 DialogPreference 类，并希望我可以使解决方案像这样工作。
我想在我的系统中实现我的 TimePreference 类，但是在调用 PreferenceActivity 时我得到一个运行时异常
04-15 16:47:31.555: W/MediaPlayer(28689): mediaplayer went away with unhandled events
04-15 16:47:31.555: W/MediaPlayer(28689): mediaplayer went away with unhandled events
04-15 16:47:31.594: D/libEGL(28689): loaded /system/lib/egl/libGLES_android.so
04-15 16:47:31.609: D/libEGL(28689): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so
04-15 16:47:31.633: D/libEGL(28689): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so
04-15 16:47:31.637: D/libEGL(28689): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so
04-15 16:47:31.793: D/OpenGLRenderer(28689): Enabling debug mode 0
04-15 16:47:36.938: D/AndroidRuntime(28689): Shutting down VM
04-15 16:47:36.938: W/dalvikvm(28689): threadid=1: thread exiting with uncaught exception (group=0x40a4c1f8)
04-15 16:47:37.024: E/AndroidRuntime(28689): FATAL EXCEPTION: main
04-15 16:47:37.024: E/AndroidRuntime(28689): java.lang.RuntimeException: Unable to start activity ComponentInfo{app.timer/app.timer.PrefsActivity}: java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.ActivityThread.access$600(ActivityThread.java:123)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.os.Handler.dispatchMessage(Handler.java:99)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.os.Looper.loop(Looper.java:137)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.ActivityThread.main(ActivityThread.java:4424)
04-15 16:47:37.024: E/AndroidRuntime(28689): at java.lang.reflect.Method.invokeNative(Native Method)
04-15 16:47:37.024: E/AndroidRuntime(28689): at java.lang.reflect.Method.invoke(Method.java:511)
04-15 16:47:37.024: E/AndroidRuntime(28689): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-15 16:47:37.024: E/AndroidRuntime(28689): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-15 16:47:37.024: E/AndroidRuntime(28689): at dalvik.system.NativeStart.main(Native Method)
04-15 16:47:37.024: E/AndroidRuntime(28689): Caused by: java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.SharedPreferencesImpl.getString(SharedPreferencesImpl.java:205)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.Preference.getPersistedString(Preference.java:1396)
04-15 16:47:37.024: E/AndroidRuntime(28689): at app.timer.TimePreference.onSetInitialValue(TimePreference.java:110)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.Preference.dispatchSetInitialValue(Preference.java:1312)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.Preference.onAttachedToHierarchy(Preference.java:1124)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.PreferenceGroup.addPreference(PreferenceGroup.java:156)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:97)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:38)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.GenericInflater.rInflate(GenericInflater.java:488)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.GenericInflater.rInflate(GenericInflater.java:493)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.GenericInflater.inflate(GenericInflater.java:326)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.GenericInflater.inflate(GenericInflater.java:263)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:269)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:1403)
04-15 16:47:37.024: E/AndroidRuntime(28689): at app.timer.PrefsActivity.onCreate(PrefsActivity.java:12)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.Activity.performCreate(Activity.java:4465)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-15 16:47:37.024: E/AndroidRuntime(28689): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
04-15 16:47:37.024: E/AndroidRuntime(28689): ... 11 more
04-15 16:47:37.137: D/dalvikvm(28689): GC_CONCURRENT freed 230K, 4% free 9362K/9671K, paused 2ms+13ms
我的 pref.xml 看起来像这样，如果我删除我的 TimePreference 就可以工作
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >
<PreferenceCategory
android:key="time_settings"
android:title="@string/time_settings"
android:summary="@string/time_settings_summary">
<app.timer.TimePreference
android:key="synchronize"
android:title="@string/synchronize"
android:summary="@string/synchronize_summary"
android:icon="@drawable/ic_dialog_time" />
</PreferenceCategory>
<PreferenceCategory
android:key="sound_cat"
android:title="@string/sound_cat"
android:summary="@string/sound_cat_summary">
<CheckBoxPreference
android:key="mute"
android:title="@string/mute"
android:summary="@string/mute_summary"
android:icon="@drawable/ic_audio_vol" />
<ListPreference
android:key="beep_interval"
android:title="@string/beep_interval"
android:summary="@string/beep_interval_summary"
android:entries="@array/beep_interval_options"
android:entryValues="@array/beep_interval_option_values"
android:defaultValue="2"
android:icon="@drawable/ic_audio_alarm" />
</PreferenceCategory>
<PreferenceCategory
android:key="screen"
android:title="@string/screen_cat"
android:summary="@string/screen_cat_summary">
<CheckBoxPreference
android:key="screen_dim"
android:title="@string/screen_dim"
android:summary="@string/screen_dim_summary"
android:icon="@drawable/ic_menu_view" />
<ListPreference
android:key="format"
android:title="@string/format"
android:summary="@string/format_summary"
android:entries="@array/format_options"
android:entryValues="@array/format_option_values"
android:defaultValue="0"
android:icon="@drawable/ic_menu_edit" />
<CheckBoxPreference
android:key="indigo"
android:title="@string/indigo"
android:summary="@string/indigo_summary"
android:icon="@drawable/brightness" />
</PreferenceCategory>
<PreferenceCategory
android:title="@string/about"
android:summary="@string/about_summary" >
<ListPreference
android:key="version_build"
android:enabled="false"
android:title="version 1.01"
android:summary="build 3" />
</PreferenceCategory>
</PreferenceScreen>
这就是 TimePreference 类
package app.timer;
import android.content.Context;
import android.content.res.TypedArray;
import android.preference.DialogPreference;
import android.text.format.DateFormat;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.TimePicker;
public class TimePreference extends DialogPreference {
protected int lastHour=0;
protected int lastMinute=0;
protected boolean is24HourFormat;
protected TimePicker picker=null;
protected TextView timeDisplay;
public TimePreference(Context ctxt) {
this(ctxt, null);
}
public TimePreference(Context ctxt, AttributeSet attrs) {
this(ctxt, attrs, 0);
}
public TimePreference(Context ctxt, AttributeSet attrs, int defStyle) {
super(ctxt, attrs, defStyle);
is24HourFormat = DateFormat.is24HourFormat(ctxt);
setPositiveButtonText("Set");
setNegativeButtonText("Cancel");
}
@Override
public String toString() {
if(is24HourFormat) {
return ((lastHour < 10) ? "0" : "")
+ Integer.toString(lastHour)
+ ":" + ((lastMinute < 10) ? "0" : "")
+ Integer.toString(lastMinute);
} else {
int myHour = lastHour % 12;
return ((myHour == 0) ? "12" : ((myHour < 10) ? "0" : "") + Integer.toString(myHour))
+ ":" + ((lastMinute < 10) ? "0" : "")
+ Integer.toString(lastMinute)
+ ((lastHour >= 12) ? " PM" : " AM");
}
}
@Override
protected View onCreateDialogView() {
picker=new TimePicker(getContext().getApplicationContext());
return(picker);
}
@Override
protected void onBindDialogView(View v) {
super.onBindDialogView(v);
picker.setIs24HourView(is24HourFormat);
picker.setCurrentHour(lastHour);
picker.setCurrentMinute(lastMinute);
}
@Override
public void onBindView(View view) {
View widgetLayout;
int childCounter = 0;
do {
widgetLayout = ((ViewGroup) view).getChildAt(childCounter);
childCounter++;
} while (widgetLayout.getId() != android.R.id.widget_frame);
((ViewGroup) widgetLayout).removeAllViews();
timeDisplay = new TextView(widgetLayout.getContext());
timeDisplay.setText(toString());
((ViewGroup) widgetLayout).addView(timeDisplay);
super.onBindView(view);
}
@Override
protected void onDialogClosed(boolean positiveResult) {
super.onDialogClosed(positiveResult);
if (positiveResult) {
picker.clearFocus();
lastHour=picker.getCurrentHour();
lastMinute=picker.getCurrentMinute();
String time=String.valueOf(lastHour)+":"+String.valueOf(lastMinute);
if (callChangeListener(time)) {
persistString(time);
timeDisplay.setText(toString());
}
}
}
@Override
protected Object onGetDefaultValue(TypedArray a, int index) {
return(a.getString(index));
}
@Override
protected void onSetInitialValue(boolean restoreValue, Object defaultValue) {
String time=null;
if (restoreValue) {
if (defaultValue==null) {
time=getPersistedString("00:00");
}
else {
time=getPersistedString(defaultValue.toString());
}
}
else {
if (defaultValue==null) {
time="00:00";
}
else {
time=defaultValue.toString();
}
if (shouldPersist()) {
persistString(time);
}
}
String[] timeParts=time.split(":");
lastHour=Integer.parseInt(timeParts[0]);
lastMinute=Integer.parseInt(timeParts[1]);;
}
}