how to retrieve info from datastore using google app engine and display it in a list view on an android app using java?

Question

I am trying to make an android app that retrieves info from google app engine datastore and display it as a listview in the android app..can anyone help me out with some code or explain what exactly needs to be done for this purpose? i have already made modifications on the server side to store data on the datastore..what i dont know is how to get that data onto the android app..i am using eclipse indigo and language is java

EDIT : I am putting my code that i am using to retrieve a set of strings from datastore and put it in a list view...the code is gonna look all haywire but i request you to bear with me and explain how exactly to write it..presently the application is force-closing whenever i get to the page where this list of retrieved strings is supposed to be displayed...

public class Display extends ListActivity
{

    private LayoutInflater mInflater;
    private Vector<RowData> data;
RowData rd;

static String[] title;
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.displaylayout);


    MyRequestFactory factory = (MyRequestFactory)Util.getRequestFactory(Display.this,MyRequestFactory.class);
    FebfourthRequest febfourthRequest = factory.febfourthRequest();
    final List<TrialDBProxy> list= new ArrayList<TrialDBProxy>();
       febfourthRequest.queryTrialDBs().fire(new Receiver<List<TrialDBProxy>>() 
    {

        @Override
        public void onSuccess(List<TrialDBProxy> arg0) {
            // TODO Auto-generated method stub
            list.addAll(arg0);
        }   


    });


    for(int i=0;i<list.size();i++)
    {
        title[i] = list.get(i).getMessage();
    }

    mInflater = (LayoutInflater) getSystemService(Activity.LAYOUT_INFLATER_SERVICE);

    data = new Vector<RowData>();

    for(int i=0;i<title.length;i++)
    {
        rd = new RowData(i,title[i]);
        data.add(rd);
    }
    int[] to = new int[] { R.id.text1, R.id.text2 };

    @SuppressWarnings("deprecation")
    Cursor mCursor = this.getContentResolver().query(People.CONTENT_URI, null,      null, null, null);
    ListAdapter adapter = new       SimpleCursorAdapter(this,R.layout.displaylayout,mCursor,title,to);
    setListAdapter(adapter);
    getListView().setTextFilterEnabled(true);

}
private class RowData 
{
protected int mId;
protected String mTitle;

RowData(int id,String title)
{
mId=id;
mTitle = title;

}
    @Override
    public String toString() 
    {
        return mId+" "+mTitle;
    }
}    '

NOTE : TrialDB is the file that contains all my fields that i want to store on the datastore. displaylayout is the xml file where i have created a listview. i am guessing the main part where i have to put code for displaying stuff is in the onCreate() method. PLEASE HELP !

Answer 1

This is already a very good starting point for learning both Google App Engine and Android Development.

I may write the steps to follow :

1. Write a Google App Engine application which reads data from datastore and gives as JSON . You can use GAE web framework, or maybe Django. After doing that, you will have a url which gives you your data in your browser.
2. Write a hello world application for Android . This step gives you an opportunity to understand and setup Android development environment.
3. Write an Android app which uses a listview with static data.
4. Extend your Android app with calling a single simple url from web , then print it on your screen.
5. Extend your application via calling your Google App Engine application url inside your app . Now you have your datastore data in your app.
6. Populate your listview with your data.