Android Open Source - Android-Parse.com-ListView-Load-More-using-OnScrollListener-Tutorial Main Activity

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License

The source code is released under:

Apache License

Java Source Code

package com.androidbegin.parseloadmore;
/*w  w w. j a  va2s . c om*/
import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;

import com.parse.ParseException;
import com.parse.ParseObject;
import com.parse.ParseQuery;

public class MainActivity extends Activity {
  // Declare Variables
  ListView listview;
  List<ParseObject> ob;
  ProgressDialog mProgressDialog;
  ListViewAdapter adapter;
  private List<Numbers> numberlist = null;
  // Set the limit of objects to show
  private int limit = 20;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    // Get the view from listview_main.xml
    setContentView(R.layout.listview_main);
    // Execute RemoteDataTask AsyncTask
    new RemoteDataTask().execute();
  }

  private class RemoteDataTask extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() {
      super.onPreExecute();
      // Create a progressdialog
      mProgressDialog = new ProgressDialog(MainActivity.this);
      // Set progressdialog title
      mProgressDialog.setTitle("Parse.com Load More Tutorial");
      // Set progressdialog message
      mProgressDialog.setMessage("Loading...");
      mProgressDialog.setIndeterminate(false);
      // Show progressdialog
      mProgressDialog.show();
    }

    @Override
    protected Void doInBackground(Void... params) {
      // Create the array
      numberlist = new ArrayList<Numbers>();
      try {
        // Locate the class table named "TestLimit" in Parse.com
        ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
            "TestLimit");
        query.orderByAscending("createdAt");
        // Set the limit of objects to show
        query.setLimit(limit);
        ob = query.find();
        for (ParseObject num : ob) {
          Numbers map = new Numbers();
          map.setNum((String) num.get("number"));
          numberlist.add(map);
        }
      } catch (ParseException e) {
        Log.e("Error", e.getMessage());
        e.printStackTrace();
      }
      return null;
    }

    @Override
    protected void onPostExecute(Void result) {
      // Locate the ListView in listview.xml
      listview = (ListView) findViewById(R.id.listview);
      // Pass the results into ListViewAdapter.java
      adapter = new ListViewAdapter(MainActivity.this, numberlist);
      // Binds the Adapter to the ListView
      listview.setAdapter(adapter);
      // Close the progressdialog
      mProgressDialog.dismiss();
      // Create an OnScrollListener
      listview.setOnScrollListener(new OnScrollListener() {

        @Override
        public void onScrollStateChanged(AbsListView view,
            int scrollState) { // TODO Auto-generated method stub
          int threshold = 1;
          int count = listview.getCount();
          
          if (scrollState == SCROLL_STATE_IDLE) {
            if (listview.getLastVisiblePosition() >= count
                - threshold) {
              // Execute LoadMoreDataTask AsyncTask
              new LoadMoreDataTask().execute();
            }
          }
        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
          // TODO Auto-generated method stub

        }

      });
    }

    private class LoadMoreDataTask extends AsyncTask<Void, Void, Void> {
      @Override
      protected void onPreExecute() {
        super.onPreExecute();
        // Create a progressdialog
        mProgressDialog = new ProgressDialog(MainActivity.this);
        // Set progressdialog title
        mProgressDialog.setTitle("Parse.com Load More Tutorial");
        // Set progressdialog message
        mProgressDialog.setMessage("Loading more...");
        mProgressDialog.setIndeterminate(false);
        // Show progressdialog
        mProgressDialog.show();
      }

      @Override
      protected Void doInBackground(Void... params) {
        // Create the array
        numberlist = new ArrayList<Numbers>();
        try {
          // Locate the class table named "TestLimit" in Parse.com
          ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
              "TestLimit");
          query.orderByAscending("createdAt");
          // Add 20 results to the default limit
          query.setLimit(limit += 20);
          ob = query.find();
          for (ParseObject num : ob) {
            Numbers map = new Numbers();
            map.setNum((String) num.get("number"));
            numberlist.add(map);
          }
        } catch (ParseException e) {
          Log.e("Error", e.getMessage());
          e.printStackTrace();
        }
        return null;
      }

      @Override
      protected void onPostExecute(Void result) {
        // Locate listview last item
        int position = listview.getLastVisiblePosition();
        // Pass the results into ListViewAdapter.java
        adapter = new ListViewAdapter(MainActivity.this, numberlist);
        // Binds the Adapter to the ListView
        listview.setAdapter(adapter);
        // Show the latest retrived results on the top
        listview.setSelectionFromTop(position, 0);
        // Close the progressdialog
        mProgressDialog.dismiss();
      }
    }

  }

}

Java Source Code List

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