来自sqlite的Android Listview

Question

I have been struggling for now days What have I done wrong so that I did not get my data on my listview

// This is the function inside database class

public ArrayList<HashMap<String, String>> getMessage(){
        ArrayList<HashMap<String, String>> message = new ArrayList<HashMap<String, String>>();
        String selectQuery = "SELECT  * FROM " + TABLE_MESSAGE;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        if (cursor.moveToFirst()) {
            do {
            HashMap<String, String> map = new HashMap<String, String>();
            map.put("message_sno", cursor.getString(0));
            map.put("message_sender", cursor.getString(1));
            map.put("message_subject", cursor.getString(2));
            map.put("message_date", cursor.getString(3));
            map.put("message_read_flag", cursor.getString(4));
            } while (cursor.moveToNext());
        }
        // return contact list
        return message;
    }

ANd the following is in my activity that extends ListActivity

ArrayList<HashMap<String, String>> emaillist = db.getMessage();
        if(emaillist.size()!=0) {
            Toast.makeText(getApplicationContext(), "this" + emaillist.get(1), Toast.LENGTH_SHORT).show();
            ListView lv = getListView();

            /*<!-- android:id="@+id/inboxlist" -->*/
            ListAdapter adapter = new SimpleAdapter( InboxActivity.this, emaillist,
                    R.layout.inbox_list_item,
                    new String[] {"message_sender","message_subject","message_date","message_read_flag"}, new int[] {
                     R.id.from,R.id.subject,R.id.date,R.id.unread});
            setListAdapter(adapter);
        }

Answer 1

For me I use always this method and it work fine :)

- Frist : -> I declare my variables :

private ListView lv; //My listview that will contain the informations
DBHelper helper = new DBHelper(this); //DBHelper is the class that contain my database on SQLite
private SQLiteDatabase db; //An instance of SQLiteDatabase that will contain my Database 
private Cursor cursor; //A cursor for the query 
public SimpleCursorAdapter adapter ; //The adapter of my ListView   

- Second : -> I create my ViewBinder :

public static ViewBinder viewBinder = new ViewBinder() {

    @Override
    public boolean setViewValue(View view, Cursor cursor, int columnIndex) {
        return false;
    }
};

- Thirdly : -> I declare two tables (The first table contain names of column that I want to display, and the seconde TextView or ImageView... That will contain that informations) :

static final String[] FROM = { "name", "image" };
static final int[] TO = { R.id.txt_name, R.id.img };

- fourthly : -> I declare my listview on the onCreate() method :

lv = (ListView) findViewById(R.id.list);

- fifthly : -> I create my class ViewHolder that contain the object that will contain the information :

static class ViewHolder {

    private TextView txtName;
    private ImageView img;

    public ViewHolder(View vue) {

        txtName = (TextView) vue.findViewById(R.id.txt_name);
        img =(ImageView) vue.findViewById(R.id.img);
    }
}

- sixthly : -> I create my class of arrayAdapter :

class CustomAdapter extends SimpleCursorAdapter {

    Activity context;
    Cursor c;

    @SuppressWarnings("deprecation")
    public CustomAdapter(Activity context, int layout, Cursor c,
            String[] from, int[] to) {
        super(context, layout, c, from, to);
        this.context = context;
        this.c = c;
        Log.i("custom", "" + c.getCount());
    }
    @Override
    public View newView(Context context, Cursor cursor, ViewGroup parent) {
        LayoutInflater inflater = getLayoutInflater();
        View row = inflater.inflate(R.layout.informations, null);
        //layout.informations is the layout that contain the textview and image view that will contain my informations
        ViewHolder wrapper = new ViewHolder(row);
        row.setTag(wrapper);

        return (row);
    }
    @Override
    public void bindView(View view, Context context, Cursor cursor) {
        ViewHolder wrapper = (ViewHolder) view.getTag();

        int n_name = c.getColumnIndex("name");

        //Example how i fill my image from informations of SQLite
        if (c.getString(n_name).equals("Suite royale")) {
            wrapper.imge.setImageResource(R.drawable.suite_royale);
        }
        if (c.getString(n_name).equals("Suite familiale")) {
            wrapper.img.setImageResource(R.drawable.suite_familiale);
        }
        wrapper.txtName.setText(c.getString(n_name));
    }
}

- Finally : -> In my onResume() method :

db = helper.getReadableDatabase();
cursor = db.query("Name_of_table", null, null, null, null, null,"_id DESC");
//it's like the SQL query : SELECT * FROM Name_of_table
startManagingCursor(cursor);
adapter = new SimpleCursorAdapter(getApplicationContext(), R.layout.informations, cursor, FROM, TO);
adapter.setViewBinder(viewBinder);
lv.setAdapter(adapter);
SimpleCursorAdapter chambres = new CustomAdapter(this, R.layout.informations,cursor, FROM, TO);
lv.setAdapter(chambres);

//Just doing this you can see your informations in your ListView and if you want a clickListener on your line of the listView just add the code below :

lv.setOnItemClickListener(new OnItemClickListener(){

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int position,
                long id) {
            Cursor c = db.query("Name_of_table", null, "_id="+(lv.getCount()-position), null, null, null,null);
//== SELECT * FROM Name_of_table WHERE _id = Id_Selected, so you need an id called (_id) on your table his type is INT AUTO_INCREMANTE for example
            c.moveToFirst();
            Log.i("position", ""+position);
            Log.i("taille","Cursor :"+c.getCount());
            String name= c.getString(c.getColumnIndex("name"));
            Toast.makeText(getBaseContext(), "Name selected is : " + name, Toast.LENGTH_SHORT).show();
            }
        }

    });

I hope this will help you, good luck :)

Answer 2

In your getMessage() method, you instantiate the ArrayList 'message' but then never add to it. You are therefore always returning an empty dataset for your adapter to use.

Within each iteration over your cursor rows, add the HashMap you have created to your ArrayList as below:

do {
HashMap<String, String> map = new HashMap<String, String>();
map.put("message_sno", cursor.getString(0));
map.put("message_sender", cursor.getString(1));
map.put("message_subject", cursor.getString(2));
map.put("message_date", cursor.getString(3));
map.put("message_read_flag", cursor.getString(4));
message.add(map);    //Add the map to the message ArrayList
} while (cursor.moveToNext());