Android Open Source - Android-Paginated-ListView-Demo Paging Buttons List View Activity

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License

The source code is released under:
GNU General Public License
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Java Source Code

/*
 * Copyright (C) 2012 Daniel Medina <http://danielme.com>
 * //from  w w w  .  ja va  2s. com
 * This file is part of "Android Paginated ListView Demo".
 * 
 * "Android Paginated ListView Demo" is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * "Android Paginated ListView Demo" is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License version 3
 * along with this program.  If not, see <http://www.gnu.org/licenses/gpl-3.0.html/>
 */
package com.danielme.blog.android.paginatedlistview.activities;

import java.util.ArrayList;
import java.util.List;

import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.danielme.blog.android.paginatedlistview.CustomArrayAdapter;
import com.danielme.blog.android.paginatedlistview.Datasource;
import com.danielme.blog.android.paginatedlistview.R;

/**
 * 
 * @author http://danielme.com
 * 
 */
public class PagingButtonsListViewActivity extends AbstractListViewActivity
{

  private int offset = 0;

  private ProgressBar progressBar;

  private Button first;

  private Button last;

  private Button prev;

  private Button next;

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

    progressBar = (ProgressBar) findViewById(R.id.progressBar1);
    textViewDisplaying = (TextView) findViewById(R.id.displaying);
    first = (Button) findViewById(R.id.buttonfirst);
    prev = (Button) findViewById(R.id.buttonprev);
    next = (Button) findViewById(R.id.buttonnext);
    last = (Button) findViewById(R.id.buttonlast);
    datasource = Datasource.getInstance();

    setListAdapter(new CustomArrayAdapter(this, new ArrayList<String>()));

    (new LoadNextPage()).execute();
  }

  private class LoadNextPage extends AsyncTask<String, Void, String>
  {
    private List<String> newData = null;

    @Override
    protected void onPreExecute()
    {
      progressBar.setVisibility(View.VISIBLE);
      loading = true;
      super.onPreExecute();
    }

    @Override
    protected String doInBackground(String... arg0)
    {
      // para que de tiempo a ver la animacin
      try
      {
        Thread.sleep(1000);
      }
      catch (InterruptedException e)
      {
        Log.e("PagingButtons", e.getMessage());
      }
      newData = datasource.getData(offset, PAGESIZE);
      return null;
    }

    @Override
    protected void onPostExecute(String result)
    {
      CustomArrayAdapter customArrayAdapter = ((CustomArrayAdapter) getListAdapter());
      customArrayAdapter.clear();
      for (String value : newData)
      {
        customArrayAdapter.add(value);
      }
      customArrayAdapter.notifyDataSetChanged();

      updateDisplayingTextView();

      loading = false;
    }

  }

  @Override
  protected void updateDisplayingTextView()
  {
    String text = getString(R.string.displayshort);
    text = String.format(text, Math.min(datasource.getSize(), offset + 1), Math.min(offset + PAGESIZE, datasource.getSize()), datasource.getSize());
    textViewDisplaying.setText(text);
    updateButtons();
    progressBar.setVisibility(View.INVISIBLE);
  }

  private void updateButtons()
  {
    if (getCurrentPage() > 1)
    {
      first.setEnabled(true);
      prev.setEnabled(true);
    }
    else
    {
      first.setEnabled(false);
      prev.setEnabled(false);
    }
    if (getCurrentPage() < getLastPage())
    {
      next.setEnabled(true);
      last.setEnabled(true);
    }
    else
    {
      next.setEnabled(false);
      last.setEnabled(false);
    }

  }

  private int getLastPage()
  {
    return (int) (Math.ceil((float) datasource.getSize() / PAGESIZE));
  }

  private int getCurrentPage()
  {
    return (int) (Math.ceil((float) (offset + 1) / PAGESIZE));
  }

  /******************** BUTTONS *************************/

  public void first(View v)
  {
    if (!loading)
    {
      offset = 0;
      (new LoadNextPage()).execute();
    }
  }

  public void next(View v)
  {
    if (!loading)
    {
      offset = getCurrentPage() * PAGESIZE;
      (new LoadNextPage()).execute();
    }
  }

  public void previous(View v)
  {
    if (!loading)
    {
      offset = (getCurrentPage() - 2) * PAGESIZE;
      (new LoadNextPage()).execute();
    }
  }

  public void last(View v)
  {
    if (!loading)
    {
      offset = (getLastPage() - 1) * PAGESIZE;
      (new LoadNextPage()).execute();
    }
  }

}
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