Android Open Source - android_rss_reader Base List Fragment

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License

The source code is released under:

Apache License

Java Source Code

/***********************************************************************************************************************
 * ==========================================
 */*  w  ww . ja v a  2s.c  o  m*/
 * Copyright (C) 2013 by Paul Oremland
 * http://www.linkedin.com/in/pauloremland
 * https://github.com/poremland
 *
 ***********************************************************************************************************************
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 *
 ***********************************************************************************************************************/
package net.oremland.rss.reader.fragments;

import net.oremland.rss.reader.R;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.*;
import android.text.*;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.*;

import java.util.*;
import java.util.Map.Entry;

import net.oremland.rss.reader.helpers.*;
import net.oremland.rss.reader.models.*;

import org.json.JSONArray;

public abstract class BaseListFragment<TModel extends BaseModel, TAdapter extends BaseAdapter>
  extends
    ListFragment
{
  private final static String MODELS_KEY = "models";
  private ListView list;
  private TAdapter adapter;
  private TreeMap<String, TModel> models;

  public interface OnModelsLoadedListener<TModel extends BaseModel>
  {
    public void onModelsLoaded(List<TModel> models);
  }

  public BaseListFragment()
  {
    // we use state management and need the onSavedInstanceState
    // and onCreate, onCreateView, and onActivityCreated methods
    // to be called for the lifecycle events of the fragment.
    setRetainInstance(false);
  }

  protected abstract void loadModelList(OnModelsLoadedListener<TModel> listener);
  protected abstract void displayModel(TModel model);
  protected abstract TAdapter createAdapter();
  protected abstract int getLayoutId();
  protected Comparator getListComparator()
  {
    return Collections.reverseOrder(Collections.reverseOrder());
  }

  protected void shouldUpdateModelList()
  {
    if(this.clearModels() || this.clearAdapter())
    {
      this.updateListView();
    }
  }

  private boolean clearAdapter()
  {
    if(this.adapter != null)
    {
      this.adapter.clear();
      return true;
    }
    return false;
  }

  private boolean clearModels()
  {
    if(this.models != null)
    {
      this.models.clear();
      return true;
    }
    return false;
  }

  @Override
  public void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
  }

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
  {
    return inflater.inflate(this.getLayoutId(), container, false);
  }

  @Override
  public void onActivityCreated(Bundle savedInstanceState)
  {
    super.onActivityCreated(savedInstanceState);

    this.initializeList();
    this.setFieldsFromBundle(this.getArguments());
    this.models = this.getSavedModels(savedInstanceState);
    this.ensureModelsTreeMapIsInitialized();
  }

  @Override
  public void onResume()
  {
    super.onResume();

    this.load();
  }

  @Override
  public void onSaveInstanceState(Bundle outState)
  {
    super.onSaveInstanceState(outState);

    this.saveModels(outState);
  }

  public void load()
  {
    if(!this.didLoadExistingModels() || !this.canCacheModels())
    {
      this.setProgressBarVisibility(View.VISIBLE);
      this.loadModelList(new OnModelsLoadedListener<TModel>()
      {
        @Override
        public void onModelsLoaded(List<TModel> models)
        {
          TreeMap<String, TModel> map = getModelMap(models);
          setModels(map);
          updateListView();
        }
      });
    }
  }

  protected boolean canCacheModels()
  {
    return true;
  }

  private boolean didLoadExistingModels()
  {
    if(this.hasModels())
    {
      updateListView();
      return true;
    }
    return false;
  }

  private boolean hasModels()
  {
    return this.models != null && this.models.size() > 0;
  }

  private void initializeList()
  {
    this.list = getListView();
    this.list.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    this.list.setOnItemClickListener(this.getListViewClickListener());
  }

  private OnItemClickListener getListViewClickListener()
  {
    return new OnItemClickListener()
    {
      public void onItemClick(AdapterView<?> parent, View view, int position, long id)
      {
        list.setItemChecked(position, true);
        list.setSelection(position);
        TModel item = (TModel)parent.getAdapter().getItem(position);
        displayModel(item);
      }
    };
  }

  protected void setFieldsFromBundle(Bundle arguments)
  {
  }

  private void ensureModelsTreeMapIsInitialized()
  {
    if(this.models == null)
    {
      this.models = this.createTreeMap();
    }
  }

  private TreeMap<String, TModel> createTreeMap()
  {
    return new TreeMap<String, TModel>(this.getListComparator());
  }

  protected void removeModel(String name)
  {
    this.ensureModelsTreeMapIsInitialized();
    this.models.remove(name);
    this.updateListView();
  }

  private TModel getModel(String name)
  {
    this.ensureModelsTreeMapIsInitialized();
    return this.models.get(name);
  }

  private TModel getModel(int position)
  {
    return (TModel)this.adapter.getItem(position);
  }

  private void setModels(TreeMap<String, TModel> models)
  {
    this.models = models;
  }

  private void updateListView()
  {
    this.ensureModelsTreeMapIsInitialized();
    this.updateListView(this.models);
    this.setProgressBarVisibility(View.GONE);
  }

  private void updateListView(TreeMap<String, TModel> items)
  {
    if(getActivity() != null)
    {
      this.adapter = this.createAdapter();
      List<TModel> models = this.getModelList(items);
      this.adapter.setModels(models);
      if(this.list != null && !this.isDetached())
      {
        this.list.setAdapter(this.adapter);
      }
    }
  }

  private List<TModel> getModelList(TreeMap<String, TModel> items)
  {
    List<TModel> models = new ArrayList<TModel>();
    for(Map.Entry<String, TModel> item : items.entrySet())
    {
      models.add(item.getValue());
    }
    return models;
  }

  private TreeMap<String, TModel> getModelMap(List<TModel> models)
  {
    TreeMap<String, TModel> map = this.createTreeMap();
    for(TModel model : models)
    {
      map.put(model.getKey(), model);
    }
    return map;
  }

  private void setProgressBarVisibility(int visible)
  {
    if(this.hasProgressBar())
    {
      getView().findViewById(R.id.progressContainer).setVisibility(visible);
    }
  }

  private boolean hasProgressBar()
  {
    return getView() != null
      && getView().findViewById(R.id.progressContainer) != null;
  }

  private void saveModels(Bundle outState)
  {
    if(this.models!= null && outState != null)
    {
      String serializedModels  = ObjectSerializer.toString(this.models);
      if(serializedModels != null)
      {
        outState.putString(MODELS_KEY, serializedModels );
      }
    }
  }

  private TreeMap<String, TModel> getSavedModels(Bundle savedInstanceState)
  {
    if(savedInstanceState != null)
    {
      String s = savedInstanceState.getString(MODELS_KEY, "");
      if(!TextUtils.isEmpty(s))
      {
        return ObjectSerializer.fromString(s);
      }
    }
    return this.models;
  }
}

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