Android Open Source - robotronic Robotronic List Activity

• Back to Development/data  ↑

From Project

Back to project page robotronic.

License

The source code is released under:

Copyright (C) 2011 by Drew Schrauf Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the So...

Java Source Code

package com.drewschrauf.robotronic.activities;
//w  ww.  j a va  2s .c  om
import java.util.ArrayList;
import java.util.List;

import android.app.ListActivity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.BaseAdapter;
import android.widget.ListView;

import com.drewschrauf.robotronic.threads.ParsingException;
import com.drewschrauf.robotronic.threads.ThreadHandler;

public abstract class RobotronicListActivity<A> extends ListActivity {
  protected List<A> items;
  protected DataFetchHandler msgHandler;
  protected ThreadHandler threadHandler;
  BaseAdapter adapter;
  ListView list;

  /** Called when the activity is first created. */
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    items = new ArrayList<A>();
    msgHandler = new DataFetchHandler();
    threadHandler = new ThreadHandler(this);

    adapter = getAdapter();
    setListAdapter(adapter);
    list = (ListView) this.findViewById(android.R.id.list);
  }

  @Override
  protected void onStart() {
    super.onStart();
    threadHandler.makeDataDownloader(getURL(), msgHandler);
  }

  @Override
  protected void onStop() {
    super.onStop();
    threadHandler.killAll();
  };

  /**
   * Returns the items used for populating the list
   * 
   * @return The list of items
   */
  public List<A> getItems() {
    return items;
  }

  /**
   * A handler for populating the ListView used on this activity
   * 
   * @author Drew
   * 
   */
  private class DataFetchHandler extends Handler {
    @Override
    public void handleMessage(Message msg) {
      if (ThreadHandler.isData(msg.what)) {

        try {
          int originalSize = items.size();
          items.addAll(0, parseData((String) msg.obj));

          if (originalSize == 0) {
            list.setAdapter(adapter);
          } else {
            adapter.notifyDataSetChanged();
            int selectedIndex = list.getFirstVisiblePosition();
            View v = list.getChildAt(0);
            int top = (v == null) ? 0 : v.getTop();
            list.setSelectionFromTop(items.size() - originalSize
                + selectedIndex, top);
          }
        } catch (ParsingException pe) {
          handleException(pe);
        }
      } else {
        handleException((Exception) msg.obj);
      }
    }
  }

  /**
   * Retrieve the ThreadHandler for the current Activity
   * 
   * @return The ThreadHandler for the current Activity
   */
  public ThreadHandler getThreadHandler() {
    return threadHandler;
  }

  /**
   * Parses the data fetched from the database or network
   * 
   * @param data
   *            A String containing the returned data
   * @return The list of items to be displayed on the screen
   */
  protected abstract List<A> parseData(String data) throws ParsingException;

  /**
   * Handle any exceptions thrown during retrieval of data
   * 
   * @param e
   *            The Exception thrown during retrieval
   */
  protected abstract void handleException(Exception e);

  /**
   * Get the adapter to be used for the ListView
   * 
   * @return An instance of BaseAdapter
   */
  protected abstract BaseAdapter getAdapter();

  /**
   * Get the URL to be used for retrieving obects to use in the ListView
   * 
   * @return A string containing the URL to retrieve the data from
   */
  protected abstract String getURL();

}

Java Source Code List

• Back to Development/data  ↑