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我是 android 编程的新手，我试图解决这个问题几个小时，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。一个按钮可以正常工作（调用活动的按钮），但另一个应该更改图片的按钮（如切换键）不起作用。我得到一个NullPointerException. 我已经跟踪了这个问题，当它传递给 onReceive 时，似乎 remoteViews 为空

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);
}
}
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1 回答 1

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我建议将其remoteViews作为局部变量，而不是将引用作为实例变量。onReceive()您可以通过在您的实现中获得新的参考，Context并使用AppWidgetManager更新您的小部件，就像您在onUpdate().

@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);
    }
}

一旦你有了新的 RemoteViews 就可以调用 setImageViewResource() 和任何你想要的。为每种情况调用 super.onReceive 也可能更好。

于 2013-03-18T16:15:14.700 回答