java - 通过 Intent 将数据从 App 传递到 Widget 时的空指针

Question

我有一个使用 Retrofit 检索的食谱列表。然后我得到食谱名称，我想更新与我的应用关联的小部件以显示所选的 recipeName。 recipeName 反射(reflect)在我的 RecyclerView 适配器中。

当用户点击 RecylcerView 中的项目时，我想更新应用程序的关联小部件。

下面是 RecyclerView 的适配器，其中我有 .setOnClickListener() 方法并通过 Intent 传递我的所有数据.

        @Override
public void onBindViewHolder(@NonNull MyAdapter.ViewHolder holder, final int position) {
        String id = mRecipeDataSet.get(position).getId();
        //The recipe name I want to pass to my widget
        final String recipeName = mRecipeDataSet.get(position).getName();
        holder.mTextView.setText(id);
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(con, BakingWidgetProvider.class);
                intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
                int[] ids = AppWidgetManager.getInstance(con).getAppWidgetIds(new ComponentName(con, BakingWidgetProvider.class));
                if(ids != null && ids.length > 0) {
                    intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids);
                    intent.putExtra(RECIPE_NAME, recipeName);
                    con.sendBroadcast(intent);
                }
                Intent i = new Intent(con, IndividualRecipeActivity.class);
                Bundle bundle = new Bundle();
                bundle.putParcelableArrayList("Recipe_List", (ArrayList<? extends Parcelable>) mRecipeDataSet);
                i.putExtras(bundle);
                i.putExtra("Position",position);
                con.startActivity(i);
            }
        });

}

下面是管理我的小部件的 BakingWidgetProvider 类。每次用户点击 RecyclerView 中的新项目时，我都想更新小部件界面:

公共(public)类 BakingWidgetProvider 扩展 AppWidgetProvider {

private static final String RECIPE_NAME = "RECIPE_NAME";
public static final String ACTION_TEXT_CHANGED = "kitchenpal.troychuinard.com.kitchenpal.TEXT_CHANGED";
private static String mRecipeName;

static void updateAppWidget(Context context, AppWidgetManager appWidgetManager,
                            int appWidgetId) {

    CharSequence widgetText = context.getString(R.string.appwidget_text);
    // Construct the RemoteViews object
    RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.baking_widget_provider);
    Log.v("WIDGET", mRecipeName);
    views.setTextViewText(R.id.selected_recipe, mRecipeName);
    Intent intent = new Intent(context, MainActivity.class);
    PendingIntent pIntent = PendingIntent.getActivity(context, 0, 
     intent, 0);
    //TODO: Why isn't my widget launching my MainActivity onClick?
    //TODO: I am trying to add a ListView of ingredients to my Widget 
     but have no idea where to begin
    views.setOnClickPendingIntent(R.id.chef, pIntent);

}

@Override
public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
    // There may be multiple widgets active, so update all of them
    for (int appWidgetId : appWidgetIds) {
        updateAppWidget(context, appWidgetManager, appWidgetId);
    }
}

@Override
public void onEnabled(Context context) {
    // Enter relevant functionality for when the first widget is created
}

@Override
public void onDisabled(Context context) {
    // Enter relevant functionality for when the last widget is disabled
}

//TODO: I cannot pass data from MyAdapter to the BakingWidgerProvider. I am simply trying to display the most recently
//TODO: selected recipe on the widget. I have scoured StackOverflow to no avail
@Override
public void onReceive(Context context, Intent intent) {
    if (intent.getAction().equals(ACTION_TEXT_CHANGED)) {
        // handle intent here
        mRecipeName = intent.getStringExtra(RECIPE_NAME);
    }
    super.onReceive(context, intent);

     //        if(intent.getAction().equals("UPDATE_ACTION")) {
     //            mRecipeName = intent.getStringExtra(RECIPE_NAME);
     //            int[] appWidgetIds = 


   intent.getExtras().getIntArray(AppWidgetManager.EXTRA_APPWIDGET_IDS);
     //            if (appWidgetIds != null && appWidgetIds.length > 0) 
     {
     //                this.onUpdate(context, 
     AppWidgetManager.getInstance(context), appWidgetIds);
     //            }
     //        } else {
     //            super.onReceive(context, intent);
     //        }
     //    }
        }
      }

更新:我已经包含了用于包含 .onReceive() 覆盖的代码，并且我在此覆盖方法中设置了字段。然后我尝试使用它来更新我在 .onUpdateAppWidget() 中的界面，但是小部件没有更新基于 mRecipeName 字段的 TextView，因为 mRecipeName 字段为空。

Answer 1

您应该在 AppWidgetClass 中覆盖 onReceive。这会接收广播的 Intent ，因此您可以从中检索数据

@Override
public void onReceive(Context context, Intent intent) {
    super.onReceive(context, intent);
    //Insert code here
}

然后继续添加您的代码以从 Intent 接收/分配数据。