如何在Android中使用setOnScrollListener实现更多加载功能

Question

我已经实现了一个android应用。 当用户向下滚动列表视图时，我想使用加载更多功能。 我将setOnScrollListener用于列表视图，但是在向下滚动列表视图时，它没有显示加载更多项目。
MainActivity

public class MainActivity extends Activity {

    private ActionBar actionBar;

    private ListView listView;

    DBHelper dbHelper;

    ArrayList<Personinfo> list;

    AdapterFilter adapterfilter;

    Personinfo personinfo;

    boolean isLoading = false;

    static int count = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        count = count + 10;
        actionBar = getActionBar();
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setBackgroundDrawable(new ColorDrawable(Color.parseColor("#03A9F4")));
        list = new ArrayList<Personinfo>();
        dbHelper = new DBHelper(this);
        listView = (ListView) findViewById(R.id.listView);
        initList(); 
        adapterfilter = new AdapterFilter(this, R.layout.child_listview, list);
        listView.setOnScrollListener(new OnScrollListener() {

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                // TODO Auto-generated method stub
            }
            @Override
            public void onScroll(AbsListView view, int firstVisibleItem,
                    int visibleItemCount, int totalItemCount) {
                // TODO Auto-generated method stub
                int lastIndexInScreen = visibleItemCount + firstVisibleItem;
                if (lastIndexInScreen >= totalItemCount && !isLoading) {
                    isLoading = true;
                    loadMore();
                }
            }
        });

        listView.setAdapter(adapterfilter);
        listView.setTextFilterEnabled(true);
    }

    public void initList() {
        list = new ArrayList<Personinfo>();
        dbHelper.openDataBase();
        Cursor cursor = dbHelper.Get_ContactDetails(count);
        cursor.moveToFirst();
        do {
            String name = cursor.getString(0);
            String phoneno = cursor.getString(1);
            Personinfo personinfo = new Personinfo(name, phoneno);
            list.add(personinfo);
        } while (cursor.moveToNext());
        dbHelper.close();
        cursor.close();
    }

    public void loadMore() {
        list = new ArrayList<Personinfo>();
        dbHelper.openDataBase();
        Cursor cursor = dbHelper.Get_ContactDetails(count);
        if (list.size() <= 90) { // Limit the number of items to 100 (stop
                                    // loading when reaching 100 items)
            cursor.moveToFirst();
            do {
                String name = cursor.getString(0);
                String phoneno = cursor.getString(1);
                Personinfo personinfo = new Personinfo(name, phoneno);
                list.add(personinfo);
            } while (cursor.moveToNext());
            dbHelper.close();
            cursor.close();
            adapterfilter.notifyDataSetChanged();
            isLoading = false;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.activity_main_actions, menu);
        // Associate searchable configuration with the SearchView
        SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
        SearchView searchView = (SearchView) menu.findItem(R.id.action_search)
                .getActionView();
        searchView.setSearchableInfo(searchManager
                .getSearchableInfo(getComponentName()));
    SearchView.OnQueryTextListener textChangeListener = new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextChange(String newText) {
                // this is your adapter that will be filtered
                adapterfilter.getFilter().filter(newText);
                System.out.println("on text chnge text: " + newText);
                return true;
            }
            @Override
            public boolean onQueryTextSubmit(String query) {
                // this is your adapter that will be filtered
                adapterfilter.getFilter().filter(query);
                System.out.println("on query submit: " + query);
                return true;
            }
        };
        searchView.setOnQueryTextListener(textChangeListener);
        return super.onCreateOptionsMenu(menu);
    }

    /**
     * On selecting action bar icons
     * */
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Take appropriate action for each action item click
        switch (item.getItemId()) {
        case R.id.action_search:
            // search action
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }
}  

DBHelper

public class DBHelper extends SQLiteOpenHelper {

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;
    // Database Name
    private static final String DATABASE_NAME = "Demo.sqlite";
    private static final String DB_PATH_SUFFIX = "/databases/";
    static Context ctx;

    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        ctx = context;
    }

    // Getting single contact
    public Cursor Get_ContactDetails(int count) {
    //public Cursor Get_ContactDetails() {
        SQLiteDatabase db = this.getReadableDatabase();
        String query = "SELECT col_1, col_2 FROM agrawalSurnameDataDemo limit 10 offset "+ count;
        //String query = "SELECT col_1, col_2 FROM agrawalSurnameDataDemo";
        Cursor cursor = db.rawQuery(query, null);
        cursor.moveToFirst();

        do {
            cursor.getString(0);
            cursor.getString(1);
            // return details;
        } while (cursor.moveToNext());
        return db.rawQuery(query, null);
    }

    public void CopyDataBaseFromAsset() throws IOException {

        InputStream myInput = ctx.getAssets().open(DATABASE_NAME);

        // Path to the just created empty db
        String outFileName = getDatabasePath();

        // if the path doesn't exist first, create it
        File f = new File(ctx.getApplicationInfo().dataDir + DB_PATH_SUFFIX);
        if (!f.exists())
            f.mkdir();

        // Open the empty db as the output stream
        OutputStream myOutput = new FileOutputStream(outFileName);

        // transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }

        // Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();

    }

    private static String getDatabasePath() {
        return ctx.getApplicationInfo().dataDir + DB_PATH_SUFFIX
                + DATABASE_NAME;
    }

    public SQLiteDatabase openDataBase() throws SQLException {
        File dbFile = ctx.getDatabasePath(DATABASE_NAME);

        if (!dbFile.exists()) {
            try {
                CopyDataBaseFromAsset();
                System.out.println("Copying sucess from Assets folder");
            } catch (IOException e) {
                throw new RuntimeException("Error creating source database", e);
            }
        }

        return SQLiteDatabase.openDatabase(dbFile.getPath(), null,
                SQLiteDatabase.NO_LOCALIZED_COLLATORS
                        | SQLiteDatabase.CREATE_IF_NECESSARY);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }
}    

AdapterFilter

public class AdapterFilter extends ArrayAdapter<Personinfo>{
    ArrayList<Personinfo> list = new ArrayList<Personinfo>();
    Context context;
    LayoutInflater inflater;


    public AdapterFilter(Context context, int resource, ArrayList<Personinfo> list) {
        super(context, resource);
        this.list = list;
        this.context = context;
        inflater = LayoutInflater.from(this.context);
    }


    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return list.size();
    }

    @Override
    public Personinfo getItem(int position) {
        // TODO Auto-generated method stub
        return list.get(position);
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub

        ViewHolder viewHolder;

        if (convertView == null) {
            convertView = inflater.inflate(R.layout.child_listview, parent,
                    false);
            viewHolder = new ViewHolder(convertView);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        final Personinfo personinfo = (Personinfo) getItem(position);

        viewHolder.txtName.setText(personinfo.getName());
        viewHolder.txtPhone.setText(personinfo.getPhoneno());
        viewHolder.txtName.setSelected(true);
        viewHolder.imageButtonCalling.setOnClickListener(new OnClickListener() {
            // Calling on selected number
            @Override
            public void onClick(View v) {

                // TODO Auto-generated method stub
                Toast.makeText(context, "number button Clicked",
                        Toast.LENGTH_SHORT).show();
                String selectedChildPhone = personinfo.getPhoneno();
                String phoneNo = "tel:" + selectedChildPhone.trim();
                Intent intent = new Intent(Intent.ACTION_CALL);
                intent.setData(Uri.parse(phoneNo));
                context.startActivity(intent);
            }
        });
        viewHolder.imageButtonMessage.setOnClickListener(new OnClickListener() {
            // Sending sms to whatsapp
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Toast.makeText(context, "meesaage button Clicked",
                        Toast.LENGTH_SHORT).show();
                String selectedChildPhone = personinfo.getPhoneno();
                Uri mUri = Uri.parse("smsto:" + selectedChildPhone);
                Intent mIntent = new Intent(Intent.ACTION_SENDTO, mUri);
                mIntent.setPackage("com.whatsapp");
                mIntent.putExtra("sms_body", "The text goes here");
                mIntent.putExtra("chat", true);
                context.startActivity(mIntent);
            }
        });

        return convertView;
    }


    private class ViewHolder {
        TextView txtName, txtPhone;
        ImageButton imageButtonCalling, imageButtonMessage;

        public ViewHolder(View item) {
            txtName = (TextView) item.findViewById(R.id.person_name);
            txtPhone = (TextView) item.findViewById(R.id.phoneno);
            imageButtonCalling = (ImageButton) item.findViewById(R.id.imageButtonCalling);
            imageButtonMessage = (ImageButton) item.findViewById(R.id.imageButtonMessage);


        }
    }

}  

请帮助我，我哪里错了！

Answer 1

这段代码对我来说很好用。 我每次加载10行并将其添加到适配器中，并且我有一个int变量totalNum ，它引用数据库中的总行数，并且布尔值loading告诉我ListView是否正在加载

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 position = firstVisibleItem + visibleItemCount;

        if (position >= totalItemCount && totalItemCount > 0 && totalItemCount < totalNum && !loading) {
            loading = true;
            // write what you want here
        }

    }
});

Answer 2

Try this:-

private boolean mHasRequestedMore;
private int preLast;

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

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

                    if (!mHasRequestedMore) {
                        final int lastItem = firstVisibleItem + visibleItemCount;

                        if (lastItem == totalItemCount) 
                        {
                                if (preLast != lastItem) {
                                    preLast = lastItem;
                                     loadMore();
                                }
                        }
                    }
                }
            );