现在的问题是您可以显示从活动AlertDialogs仅。这不是上下文的问题。

虽然这不是一个好主意，显示从接收器的（***是使用通知），但是如果你想这样做，你可以创建一个Activity为对话框并显示

I want to show an Alert Dialog via AlertDialogManager class to a non-activity class DeviceAdminReceiverSample's method onDisabled, but whenever I call alertDialog via that method it generates error with following text

Error

06-12 12:01:19.923: E/AndroidRuntime(468): FATAL EXCEPTION: main
06-12 12:01:19.923: E/AndroidRuntime(468): java.lang.RuntimeException: Unable to start           
receiver com.android.remotewipedata.DeviceAdminReceiverSample:   
android.view.WindowManager$BadTokenException: Unable to add window -- token null is not   
for an application

I know the issue is with context thing but I don't know what to put there so that it work, I tried this, getApplicationContext() but all vain. My code for both classes is below

AlertDialogManager

public class AlertDialogManager {

public void showAlertDialog(Context context, String title, String message,
        Boolean status) {
    final AlertDialog alertDialog = new AlertDialog.Builder(context).create();
    alertDialog.setTitle(title);
    alertDialog.setMessage(message);

    if (status != null)
        alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                alertDialog.dismiss();
            }
        });
    alertDialog.show();
}

}

DeviceAdminReceiverSample

public class DeviceAdminReceiverSample extends DeviceAdminReceiver {
static final String TAG = "DeviceAdminReceiver";
AlertDialogManager alert = new AlertDialogManager();

/** Called when this application is no longer the device administrator. */
@Override
public void onDisabled(Context context, Intent intent) {
    super.onDisabled(context, intent);
    Toast.makeText(context, R.string.device_admin_disabled,
            Toast.LENGTH_LONG).show();
    // intent.putExtra("dialogMessage", "Device admin has been disabled");
    // intent.setClass(context, DialogActivity.class);
    // intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    // context.startActivity(intent);
    alert.showAlertDialog(context, "Alert",
            "Device admin has been disabled", true);
}

The problem is 'You can show AlertDialogs from Activity only'. This is not an issue of context.

Although this is not a good idea to show dialog from receiver (better is to use Notification), But if you want to do so you can create an Activity as dialog and show