如何显示来自非 activity class 的警报对话框

Question

我已经知道 AlertDialog 不能从非 activity class 调用。我也知道我无法在静态方法中使用 AlertDialog（因此我可以从 class 中调用该方法）。

我想要实现的目标是当用户收到推送通知并点击它时，调用 Receiver class。在某些情况下，class 正在开始一个新的 activity，但在其他情况下，它应该显示 alert 说类似的话（这并不是真正写在警报中）：You have that activity already running, please stop the activity to start the one from notification.

我无法实现，有什么想法吗？

代码（接收方 class）：

@Override
public void onPushOpen(Context context, Intent intent) {
    JSONObject pushData = null;
    String notificationMessage = "";
    Boolean inBattle = getInBattleFromCache(context);
    if (inBattle){
        showWarningAlert();
    }else {
        try {
            pushData = new JSONObject(intent.getStringExtra("com.parse.Data"));
            notificationMessage = pushData.optString("alert");
        } catch (JSONException e) {
            e.printStackTrace();
        }
        Log.e("Push", "Clicked:" + pushData);
        if (notificationMessage.contains("Your battle")) {
            moveToMainActivity(context);
        } else {
            moveToArena(notificationMessage, true, context);
        }
    }

}

private void showWarningAlert() {
    AlertDialog alertDialog = new AlertDialog.Builder(NoIdeaWhatShouldBeHere.this).create();
    alertDialog.setTitle("Warning");
    alertDialog.setMessage("You are currently in a battle");
    alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK",
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            });
    alertDialog.show();
}

当我在其中放置 context 变量时，它会抛出此错误：

05-11 15:27:07.665    1692-1692/com.parse.starter E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start receiver com.parse.starter.Receiver: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
        at android.app.ActivityThread.handleReceiver(ActivityThread.java:2431)
        at android.app.ActivityThread.access00(ActivityThread.java:141)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1332)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5103)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:525)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
        at android.view.ViewRootImpl.setView(ViewRootImpl.java:563)
        at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:269)
        at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
        at android.app.Dialog.show(Dialog.java:281)
        at com.parse.starter.Receiver.showWarningAlert(Receiver.java:61)
        at com.parse.starter.Receiver.onPushOpen(Receiver.java:32)
        at com.parse.ParsePushBroadcastReceiver.onReceive(ParsePushBroadcastReceiver.java:115)
        at android.app.ActivityThread.handleReceiver(ActivityThread.java:2424)
            at android.app.ActivityThread.access00(ActivityThread.java:141)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1332)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

This 没有帮助。

Answer 1

private void showWarningAlert(Context context) { //Added argument
    AlertDialog alertDialog = new AlertDialog.Builder(context).create(); //Use context
    alertDialog.setTitle("Warning");
    alertDialog.setMessage("You are currently in a battle");
    alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK",
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int which) {
                    dialog.dismiss();
                }
            });
    alertDialog.show();
}

假设 onPushOpen 中的上下文是正确的

    showWarningAlert(context);

如何显示来自非 activity class 的警报对话框

How to show alert dialog from a non activity class

android

android-alertdialog

android-activity