Android loaders, the way to go?

Question

I am used to building lists in android using adapters. If I need some long-to-get data, I use an asynctask, or a simple runnable, to update the data structure on which the adapt

Answer 1

In case someone is looking for the loader version of my previous example : here it is :

package com.sof.test.loader;

import java.util.ArrayList;
import android.app.LoaderManager;
import java.util.List;

import android.app.ListActivity;
import android.content.AsyncTaskLoader;
import android.content.Context;
import android.content.Loader;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.ArrayAdapter;
import android.widget.TextView;

/** The activity. */
public class LoaderTestActivity2 extends ListActivity implements
        LoaderManager.LoaderCallbacks> {

    private DataSourceOrDomainModel dataSourceOrDomainModel = new DataSourceOrDomainModel();
    private List listPerson;
    private PersonListAdapter personListAdapter;
    private TextView emptyView;
    private Loader> personLoader;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        listPerson = new ArrayList();
        personListAdapter = new PersonListAdapter(listPerson);
        setListAdapter(personListAdapter);
        personLoader = new PersonLoader(this, dataSourceOrDomainModel, new ProgressHandler() );
        setUpEmptyView();
        getLoaderManager().initLoader(0, null, this);
        personLoader.forceLoad();
    }

    public void setUpEmptyView() {
        emptyView = new TextView(this);
        emptyView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
                LayoutParams.WRAP_CONTENT));
        emptyView.setVisibility(View.GONE);
        ((ViewGroup) getListView().getParent()).addView(emptyView);
        getListView().setEmptyView(emptyView);
    }

    public void publishProgress(int progress) {
        emptyView.setText("Loading data :" + String.valueOf(progress) + " %");
    }

    @Override
    public Loader> onCreateLoader(int arg0, Bundle arg1) {
        return personLoader;
    }

    @Override
    public void onLoadFinished(Loader> personLoader, List result) {
        listPerson.clear();
        listPerson.addAll(result);
        personListAdapter.notifyDataSetChanged();
    }

    @Override
    public void onLoaderReset(Loader> arg0) {
        listPerson.clear();
        personListAdapter.notifyDataSetChanged();
    }

    /** List item view factory : the adapter. */
    private class PersonListAdapter extends ArrayAdapter {

        public PersonListAdapter(List listPerson) {
            super(LoaderTestActivity2.this, 0, listPerson);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            if (convertView == null) {
                convertView = new PersonView(getContext());
            }
            PersonView personView = (PersonView) convertView;
            personView.setPerson((Person) getItem(position));
            return personView;
        }
    }

    private class ProgressHandler implements ProgressListener {

        @Override
        public void personLoaded(final int count, final int total) {
            runOnUiThread( new Runnable() {
                @Override
                public void run() {
                    publishProgress(100 * count / total);                   
                }
            });
        }
    }
}

 class PersonLoader extends AsyncTaskLoader> {

    private DataSourceOrDomainModel dataSourceOrDomainModel;
    private ProgressListener progressHandler;

    public PersonLoader(Context context, DataSourceOrDomainModel dataSourceOrDomainModel, ProgressListener progressHandler ) {
        super(context);
        this.dataSourceOrDomainModel = dataSourceOrDomainModel;
        this.progressHandler = progressHandler;
    }

    @Override
    public List loadInBackground() {
        return dataSourceOrDomainModel.getListPerson( progressHandler );
    }
}

It would be more difficult to add support (support librairy) to this example as there is no equivalent of ListAcitivity in the support librairy. I would have either to create a ListFragment or create an FragmentActivity and give it a layout including a list.