Add a new item to recyclerview programmatically?

问题:

I'm still trying to get my head around recyclerview. I have an arraylist, that I use to initialize a recycler view with.

How can I add new items to the recycler view post setting an adapter and layoutmanager?

private void initData() {
        mItems = new ArrayList<String>();
        for (int i = 0; i < ITEMS_COUNT; i++) {
            mItems.add("Item " + (i + 1));
        }
    }

    private void initRecyclerView() {
        mRecentRecyclerView = (RecyclerView) findViewById(R.id.recentrecyclerView);
        mRecentRecyclerView.setHasFixedSize(true);
        mRecentLayoutManager = new LinearLayoutManager(this);
        mRecentRecyclerView.setLayoutManager(mRecentLayoutManager);



        mAdapter = new RecyclerView.Adapter<CustomViewHolder>() {
            @Override
            public CustomViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
                View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.notice_snippet
                        , viewGroup, false);
                return new CustomViewHolder(view);
            }

            @Override
            public void onBindViewHolder(CustomViewHolder viewHolder, int i) {
                viewHolder.noticeSubject.setText(mItems.get(i));
            }

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

        };
        mRecentRecyclerView.setAdapter(mAdapter);

    private class CustomViewHolder extends RecyclerView.ViewHolder {

        private TextView noticeSubject;

        public CustomViewHolder(View itemView) {
            super(itemView);

            noticeSubject = (TextView) itemView.findViewById(R.id.notice_subject);
        }
    }

So basically after I initdata() and initRecyclerView(), how do i add a new item to the RecyclerView??

回答1:

First add your item to mItems and then use:

mAdapter.notifyItemInserted(mItems.size() - 1);

this method is better than using:

mAdapter.notifyDataSetChanged();

in performance.

回答2:

simply add to your data structure ( mItems ) , and then notify your adapter about dataset change

private void addItem(String item) {
  mItems.add(item);
  mAdapter.notifyDataSetChanged();
}

addItem("New Item");

回答3:

if you are adding multiple items to the list use this:

mAdapter.notifyItemRangeInserted(startPosition, itemcount);

This notify any registered observers that the currently reflected itemCount items starting at positionStart have been newly inserted. The item previously located at positionStart and beyond can now be found starting at position positinStart+itemCount

existing item in the dataset still considered up to date.

回答4:

this.runOnUiThread(new Runnable() {
     public void run() {
         mAdapter.notifyDataChanged()
     }
 });