当单击 ListActivity 中的项目时，我试图显示一个 AlertDialog。我的应用程序在 TabActivity 的选项卡下显示 ListActivity，并且 AlertDialog 显示没有问题。ListActivity（称为 FavouritesActivity）几乎直接来自 Android 文档，具有以下设置：
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
//... code to set the strings station, number, route, and direction
FavouritesActivity.this.confirmSend(position);
}
});
进而
public void confirmSend(final int position) {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Are you sure?")
.setCancelable(true)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
//... some code to run here
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int id) {
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
}
但是，在 TabActivity 的第二个选项卡中，我有一个 ActivityGroup，它使用 LocalActivityManager 启动另一个 ListActivity，就像这样（同样，与在线选项卡下嵌套列表的教程几乎没有变化）：
public class MyGroupActivity extends ActivityGroup {
// Keep this in a static variable to make it accessible for all the nesten activities, lets them manipulate the view
public static MyGroupActivity group;
// Need to keep track of the history if you want the back-button to work properly, don't use this if your activities requires a lot of memory.
private ArrayList<View> history;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.history = new ArrayList<View>();
group = this;
// Start the root activity withing the group and get its view
View view = getLocalActivityManager().startActivity("FirstListActivity", new
Intent(this,FirstListActivity.class)
.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP))
.getDecorView();
// Replace the view of this ActivityGroup
replaceView(view);
}
public void replaceView(View v) {
// Changes this Groups View to the new View.
setContentView(v);
}
这里的 FirstListActivity 是一个 ListActivity，它是系列中的第一个。用户选择一个项目并显示另一个 ListActivity，代码如下：
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Intent intent = new Intent();
intent.setClass(FirstListActivity.this, TheNextListActivity.class);
// Create View using the Group Activity's LocalActivityManager
View newview = MyGroupActivity.group.getLocalActivityManager()
.startActivity("show_routes", intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP))
.getDecorView();
// And replace the view
MyGroupActivity.group.replaceView(newview);
}
});
本系列中的最后一个 ListActivity 与我展示的第一个 ListActivity 示例具有完全相同的 onItemClick 侦听器和关联的 confirmSend 函数（确实有效），但是现在当用户单击一个项目时，AlertDialog 无法显示并且应用程序停止出乎意料的是，使用此调试输出：
W/WindowManager( 570): Attempted to add application window with unknown token android.os.BinderProxy@4373af30. Aborting.
D/AndroidRuntime( 1953): Shutting down VM
W/dalvikvm( 1953): threadid=3: thread exiting with uncaught exception (group=0x4000fe70)
E/AndroidRuntime( 1953): Uncaught handler: thread main exiting due to uncaught exception
E/AndroidRuntime( 1953): android.view.WindowManager$BadTokenException: Unable to add window -- token android.app.LocalActivityManager$LocalActivityRecord@43750f98 is not valid; is your activity running?
E/AndroidRuntime( 1953): at android.view.ViewRoot.setView(ViewRoot.java:425)
E/AndroidRuntime( 1953): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:178)
E/AndroidRuntime( 1953): at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91)
E/AndroidRuntime( 1953): at android.view.Window$LocalWindowManager.addView(Window.java:392)
E/AndroidRuntime( 1953): at android.app.Dialog.show(Dialog.java:231)
E/AndroidRuntime( 1953): at com.ttcsms.LastListActivity.confirmSend(LastListActivity.java:119)
E/AndroidRuntime( 1953): at com.ttcsms.LastListActivity$1.onItemClick(LastListActivity.java:66)
E/AndroidRuntime( 1953): at android.widget.AdapterView.performItemClick(AdapterView.java:283)
E/AndroidRuntime( 1953): at android.widget.ListView.performItemClick(ListView.java:3132)
E/AndroidRuntime( 1953): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1620)
E/AndroidRuntime( 1953): at android.os.Handler.handleCallback(Handler.java:587)
E/AndroidRuntime( 1953): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime( 1953): at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime( 1953): at android.app.ActivityThread.main(ActivityThread.java:3948)
E/AndroidRuntime( 1953): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime( 1953): at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime( 1953): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
E/AndroidRuntime( 1953): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
E/AndroidRuntime( 1953): at dalvik.system.NativeStart.main(Native Method)
I/Process ( 570): Sending signal. PID: 1953 SIG: 3
I/dalvikvm( 1953): threadid=7: reacting to signal 3
I/dalvikvm( 1953): Wrote stack trace to '/data/anr/traces.txt'
I/Process ( 1953): Sending signal. PID: 1953 SIG: 9
I/ActivityManager( 570): Process com.ttcsms (pid 1953) has died.
导致此失败的这两条通往 AlertDialog 的路线有什么区别？它似乎与 AlertDialog.Building(this) 位有关。当在 ActivityGroup 中时，它会得到错误的上下文或其他东西。我在网上找到的有关此错误的每个示例都通过在“this”和“getApplicationContext()”之间进行更改来解决，但在这种情况下，这些都不起作用。我尝试了获取上下文的其他变体，但由于我主要是随机猜测，我认为在这里寻求建议会更好。我应该传递什么上下文，或者还有什么问题？