从inputsream到列表视图将10个项目下载到下一个10个项目中

Question

In my android application, I am downloading content through an input stream. At the moment from my code all the content is loaded at once from the server and parser via an asynctask then to a listview. How can I download items from the server through an input in batches of ten from the below snippets

private String downloadData()
    {
        HttpURLConnection con=Connector.connect(urlAddress);
        if(con==null)
        {
            return null;
        }

        try
        {
            InputStream is=new BufferedInputStream(con.getInputStream());
            BufferedReader br=new BufferedReader(new InputStreamReader(is));

            String line;
            StringBuffer jsonData=new StringBuffer();


            return jsonData.toString();

        } catch (IOException e) {
            e.printStackTrace();
        }


        return null;
    }

Please how can I use the dowloaddata() I created to pull items from the server in batches of 10 then accordingly to the listview while on scroll

Answer 1

You need set scroll Listener for your list View Using:

listView.setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {

            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {

                int lastInScreen = firstVisibleItem + visibleItemCount;
                if(!loadingMore && (lastInScreen == totalItemCount)) {
                    new Thread(() -> {
                        loadingMore = true; // loadingMore is local boolean to check if you already loaded
                        runOnUiThread(() -> {
                            //Here You Can Execute your AsyncTask and update your List of Items
                            adapter.notifyDataSetChanged(); // notify the data in list of items has changed
                            loadingMore = false;
                        });

                    }).start();
                }

            }
        });

You can read this tutorial for creating ENDLESS LIST VIEW https://www.mindstick.com/Articles/1570/endless-list-view-adapter-in-android