从 activity 上的 intentservice 更新数据

Question

我有一个包含以下代码的 activity，我正在尝试通过创建 class 的实例并调用更新方法来更新 IntentService 中的数据，但它因 null 而崩溃mAdapter 的指针异常。这是将数据从 IntentService 传递到 activity 的正确方法吗？

代码：

public class MainActivity extends Activity {

    RecyclerView  rv;
    SimpleStringRecyclerViewAdapter mAdapter;

    public static final TypedValue mTypedValue = new TypedValue();
    public static int mBackground;
    public static List<String> mValues;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.cheesecake_homepage_fragment_cheese_list);

         rv = (RecyclerView) findViewById(R.id.recyclerview);
        setupRecyclerView(rv);

        send_msg("");
    }

    public void setupRecyclerView(RecyclerView recyclerView) {

        mAdapter = new SimpleStringRecyclerViewAdapter(getBaseContext(),
                getRandomSublist(Cheeses.sCheeseStrings, 3));
        recyclerView.setLayoutManager(new LinearLayoutManager(recyclerView.getContext()));
        recyclerView.setAdapter(mAdapter);
    }

    private List<String> getRandomSublist(String[] array, int amount) {
        ArrayList<String> list = new ArrayList<>(amount);
        Random random = new Random();
        while (list.size() < amount) {
            list.add(array[random.nextInt(array.length)]);
        }
        return list;
    }

    public static class SimpleStringRecyclerViewAdapter
            extends RecyclerView.Adapter<SimpleStringRecyclerViewAdapter.ViewHolder> {



        public static class ViewHolder extends RecyclerView.ViewHolder {
            public String mBoundString;

            public final View mView;
            public final ImageView mImageView;
            public final TextView mTextView;

            public ViewHolder(View view) {
                super(view);
                mView = view;
                mImageView = (ImageView) view.findViewById(R.id.avatar);
                mTextView = (TextView) view.findViewById(android.R.id.text1);
            }

            @Override
            public String toString() {
                return super.toString() + " '" + mTextView.getText();
            }
        }

        public String getValueAt(int position) {
            return mValues.get(position);
        }

        public SimpleStringRecyclerViewAdapter(Context context, List<String> items) {
            context.getTheme().resolveAttribute(R.attr.selectableItemBackground, mTypedValue, true);
            mBackground = mTypedValue.resourceId;
            mValues = items;
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.cheesecake_homepage_list_item, parent, false);
            view.setBackgroundResource(mBackground);
            return new ViewHolder(view);
        }

        @Override
        public void onBindViewHolder(final ViewHolder holder, int position) {
            holder.mBoundString = mValues.get(position);
            holder.mTextView.setText(mValues.get(position));

            holder.mView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Context context = v.getContext();
                    /*Intent intent = new Intent(context, CheeseDetailActivity.class);
                    intent.putExtra(CheeseDetailActivity.EXTRA_NAME, holder.mBoundString);

                    context.startActivity(intent);*/
                }
            });

        }

        @Override
        public int getItemCount() {
            return mValues.size();
        }
    }



    public void send_msg( String  set_text){

        new Handler(Looper.getMainLooper()).post(new Runnable() {
            @Override
            public void run() {

                List<String> uu = getRandomSublist(Cheeses.sCheeseStrings, 1);
                mValues.addAll(uu);

                mAdapter.notifyDataSetChanged();



            }
        });


    }

}

意向服务中：

MainActivity test = new MainActivity();
test.send_msg("");

Answer 1

update data from intentservice on an activity

通过创建扩展 Activity 或任何其他主要应用程序组件的 class 对象不是组件之间通信的正确方式。

对于进程内通信（如您的情况，希望将数据从 IntentService 发送到 Activity），请使用 LocalBroadcastManager

Answer 2

您不能像在 Intent 服务代码中那样使用 MainActivity 实例。有多种方法可以从服务更新 UI，例如 LocalBroadcastReceivers、Messengers、BoundedService 等

您可以找到使用 LocalBroadcastManager here

从服务更新 UI 的示例

从 activity 上的 intentservice 更新数据

update data from intentservice on an activity

android

intentservice

android-recyclerview