Question

我是Android编程的新手，我试图弄清楚这几个小时，但仍然无法让它工作。我正在创建一个有2个按钮的小部件。一个按钮工作正常（调用活动的按钮）但另一个假设更改图片的按钮（如togglekey）不起作用。我得到NullPointerException。我已经跟踪了这个问题，当它传递给onReceive

时，似乎是remoteViews为null

public class Widget extends AppWidgetProvider {
boolean status = false;
private RemoteViews remoteViews;
Button bMain;

@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager,
        int[] appWidgetIds) {
    super.onUpdate(context, appWidgetManager, appWidgetIds);

    final int n = appWidgetIds.length;
    for(int i = 0; i < n; i++){
        final int appWidgetId = appWidgetIds[i];

        remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget);

        Intent configIntent = new Intent(context, Main.class);
        configIntent.setAction("callingActivity");
        PendingIntent configPendingIntent = PendingIntent.getActivity(context,
                0, configIntent, 0);
        remoteViews.setOnClickPendingIntent(R.id.bWidgetMain,
                configPendingIntent);

        configIntent = new Intent(context, Widget.class);
        configIntent.setAction("callingibFlash");
        configPendingIntent = PendingIntent.getBroadcast(context, 0,
                configIntent, 0);
        remoteViews.setOnClickPendingIntent(R.id.ibFlash, configPendingIntent);

        appWidgetManager.updateAppWidget(appWidgetIds, remoteViews);
    }

}

@Override
public void onReceive(Context context, Intent intent) {
    if (intent.getAction().equals("callingActivity")) {
        Toast.makeText(context, "Main", Toast.LENGTH_SHORT).show();
    } else if (intent.getAction().equals("callingibFlash")) {
        remoteViews.setImageViewResource(R.id.ibFlash,
                R.drawable.flashlight_on);
    } else {
        super.onReceive(context, intent);
    }
}

@Override
public void onDeleted(Context context, int[] appWidgetIds) {
    super.onDeleted(context, appWidgetIds);
}
}

Answer 1

我建议将remoteViews作为局部变量，而不是将引用作为实例变量。您可以通过onReceive()在Context实施中获得新的参考，并使用AppWidgetManager更新您的小部件，就像在onUpdate()中一样。

@Override
public void onReceive(Context context, Intent intent){
    if (intent.getAction().equals("callingActivity")) {
        Toast.makeText(context, "Main", Toast.LENGTH_SHORT).show();
    } else if (intent.getAction().equals("callingibFlash")) {
        ComponentName thisWidget = new ComponentName(context, Widget.class);
        AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context);
        int[] appWidgetIds = appWidgetManager.getAppWidgetIds(thisWidget);
        myRefactoredUpdate(context, appWidgetManager, appWidgetIds);
        // use for loop as in onUpdate to get to your remoteViews
        final int n = appWidgetIds.length;
        for (int i = 0; i < n; i++) {
            final int appWidgetId = appWidgetIds[i];
            remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget);
            remoteViews.setImageViewResource(R.id.ibFlash, R.drawable.flashlight_on);
        }
    } else {
        super.onReceive(context, intent);
    }
}

一旦你有新的RemoteViews可以调用setImageViewResource（）和你想要的任何其他东西。为每个案例调用super.onReceive也可能更好。

Android小部件远程查看onReceive中的空值

1 个答案: