我想请你帮忙:在我的应用程序中,我只有一个活动,一个PreferenceActivity
(不需要其他活动,它只是一个简单的后台同步应用程序,因此PrefsActivity
是主/启动器)。用户设置完偏好后,勾选checkBoxPreference
,然后启动(或停止)服务。在启动时,会显示一个对话框。
但是问题在于:如果用户按返回键离开活动,再次启动它,然后尝试勾选checkBoxPref
,则prefsactivity
将崩溃。对话框不会显示。我不知道为什么,也不知道如何修复它。
这段代码与给我带来问题的那部分完全相同:
PrefsActivity.java:
package is.it.works;
// imports .....
public class PrefsActivity extends PreferenceActivity implements OnSharedPreferenceChangeListener {
SharedPreferences prefs;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.prefs);
prefs = PreferenceManager.getDefaultSharedPreferences(this);
prefs.registerOnSharedPreferenceChangeListener(this);
}// onCreate
@Override
public void onSharedPreferenceChanged(SharedPreferences preferences, String key) {
if (key.equals("checkTest")) {
showDialog(1);
}
if (key.equals("cancel")) {
dismissDialog(1);
}
}// onSPC
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case 1: {
ProgressDialog dialog = new ProgressDialog(this);
dialog.setMessage("press back twice, start the app again, and click checkbox...");
dialog.setIndeterminate(true);
dialog.setCancelable(true);
dialog.setOnCancelListener(new OnCancelListener() {
@Override
public void onCancel(DialogInterface dialog) {
prefs.edit().putBoolean("cancel", false).commit();
}
});
return dialog;
}// case
}// switch
return null;
}// onCreateDialog
}// PrefsActivity
prefs.xml:
<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
<CheckBoxPreference android:key="checkTest" android:title="test" />
</PreferenceScreen>
以及清单文件:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="is.it.works" android:versionCode="1" android:versionName="1.0">
<uses-sdk android:minSdkVersion="4" />
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".PrefsActivity" android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
日志记录错误:
09-14 10:34:34.472: ERROR/AndroidRuntime(281): Uncaught handler: thread main exiting due to uncaught exception
09-14 10:34:34.502: ERROR/AndroidRuntime(281): android.view.WindowManager$BadTokenException: Unable to add window -- token android.os.BinderProxy@43756de8 is not valid; is your activity running?
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.view.ViewRoot.setView(ViewRoot.java:456)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:177)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.view.Window$LocalWindowManager.addView(Window.java:409)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.app.Dialog.show(Dialog.java:238)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.app.Activity.showDialog(Activity.java:2413)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at is.it.works.PrefsActivity.onSharedPreferenceChanged(PrefsActivity.java:27)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.app.ApplicationContext$SharedPreferencesImpl$EditorImpl.commit(ApplicationContext.java:2727)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.preference.Preference.tryCommit(Preference.java:1199)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.preference.Preference.persistBoolean(Preference.java:1404)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.preference.CheckBoxPreference.setChecked(CheckBoxPreference.java:155)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.preference.CheckBoxPreference.onClick(CheckBoxPreference.java:143)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.preference.Preference.performClick(Preference.java:811)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.preference.PreferenceScreen.onItemClick(PreferenceScreen.java:190)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.widget.AdapterView.performItemClick(AdapterView.java:284)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.widget.ListView.performItemClick(ListView.java:3246)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1635)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.os.Handler.handleCallback(Handler.java:587)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.os.Handler.dispatchMessage(Handler.java:92)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.os.Looper.loop(Looper.java:123)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at android.app.ActivityThread.main(ActivityThread.java:4203)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at java.lang.reflect.Method.invokeNative(Native Method)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at java.lang.reflect.Method.invoke(Method.java:521)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)
09-14 10:34:34.502: ERROR/AndroidRuntime(281): at dalvik.system.NativeStart.main(Native Method)
09-14 10:34:34.522: INFO/Process(52): Sending signal. PID: 281 SIG: 3
09-14 10:34:34.532: INFO/dalvikvm(281): threadid=7: reacting to signal 3
09-14 10:34:34.592: INFO/dalvikvm(281): Wrote stack trace to '/data/anr/traces.txt'
09-14 10:34:38.533: DEBUG/dalvikvm(107): GC freed 437 objects / 21560 bytes in 136ms
09-14 10:34:39.183: INFO/global(175): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
09-14 10:34:44.632: INFO/global(175): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.
09-14 10:34:47.412: INFO/Process(281): Sending signal. PID: 281 SIG: 9
09-14 10:34:47.472: INFO/ActivityManager(52): Process is.it.works (pid 281) has died.
09-14 10:34:47.492: INFO/WindowManager(52): WIN DEATH: Window{4394f638 is.it.works/is.it.works.PrefsActivity paused=false}
经过大量Google搜索后,我认为问题出在 ProgressDialog dialog = new ProgressDialog(this);
中的 this
上。因为 this
会发生变化。但是将它更改为 getApplicationContext()
或 PrefsActivity.this
都没有帮助,问题仍然存在。请告诉我这是为什么,并且可能的解决方案有哪些!谢谢!我陷入了困境,现在我一点头绪也没有...