在“自定义列表视图”中向上滚动时，滚动位置跳至上一个列表项

我有一个包含列表视图的活动。当用户滚动到列表视图的底部时，列表将获取更多数据。当用户向下滚动时，滚动是平滑的。但是，当用户向上滚动时，列表视图倾向于将其可见项跳过一两个。

班级：

public class ListViewActivity extends Activity implements OnScrollListener {

    int id = 0;
    List dataParse = new ArrayList();
    LazyAdapter adapter;
    ListView listView;
    List richArrayList = new ArrayList();

    private int currentScrollState;
    private int currentVisibleItemCount;
    private int skipParam = 0;
    private boolean flag_loading = false;

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

        listView = (ListView) findViewById(R.id.listView);
        // Need to create the adapter constructor
        listView.setOnScrollListener(this);
        adapter = new LazyAdapter(PostListActivity.this, dataParse, richArrayList);
        listView.setAdapter(adapter);

        setStory();

    }

    public void setStory() {

        // Pull data from Parse
        HashMap params = new HashMap();
        params.put("userid", ParseUser.getCurrentUser().getObjectId());
        params.put("skip", skipParam);

        ParseCloud.callFunctionInBackground("studentsPosts", params, new FunctionCallback>>() {
            @Override
            public void done(List> data, com.parse.ParseException arg1) {
                if (data == null) {

                } else {
                    Log.e("size ", "RUNNING Size :   " + data.size());

                    if (data.size() > 0) {
                        flag_loading = false;
                        for (int i = 0; i  pFileList;
                                pFileList = (List) data.get(i).get(0).get("photos");


                                rc.setPhotosArray(pFileList);


                            }
                            if(data.get(i).get(0).getParseFile("photo") != null){
                                //Time to retrieve the photo
                                ParseFile getParseFile;
                                getParseFile = (ParseFile) data.get(i).get(0).get("photo");
                                //ParseFile getParseFile = ParseFile.this.getDataInBackground(data.get(i).get(0).getParseFile("photo"));
                                rc.setPhoto(getParseFile);
                            }

                            richArrayList.add(rc);
                            adapter.notifyDataSetChanged();
                        }
                    }
                }

            }

        });

    }

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
        this.currentScrollState = scrollState;
        this.isScrollCompleted();
    }

    private void isScrollCompleted() {
        if (this.currentVisibleItemCount >= 5 && this.currentScrollState == SCROLL_STATE_IDLE) {


        }
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        this.currentVisibleItemCount = visibleItemCount;

        Log.e("firstVisibleItem", ""+firstVisibleItem);
        Log.e("visibleItemCount", ""+visibleItemCount);
        Log.e("totalItemCount", ""+totalItemCount);
        if (firstVisibleItem + visibleItemCount == totalItemCount && totalItemCount != 0) {
            if (flag_loading == false) {
                flag_loading = true;
                Log.d("IN ON SCROLL", "NOW: " + skipParam);
                skipParam = skipParam + 10; 
                setStory();
            }

        }
    }

}

我要去哪里错了？为什么向上滚动会受到影响？