notifyDataSetChanged() with CustomAdapter and SQLite

[simone giusti]

I am not able to update Listview when database is updated.

Custom Adapter

package it.rockopera.scsremote;

/**
 * Created by Simone on 10/12/2016.
 */

import android.content.Context;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;

/**
 * Created by anupamchugh on 09/02/16.
 */
public class CustomAdapter extends ArrayAdapter<DataModel> implements View.OnClickListener{

    private ArrayList<DataModel> dataSet;
    Context mContext;

    // View lookup cache
    private static class ViewHolder {
        TextView CueLabel;
        TextView CueName;
    }

    public CustomAdapter(ArrayList<DataModel> data, Context context) {
        super(context, R.layout.lv_cues_row, data);
        this.dataSet = data;
        this.mContext=context;
    }


    @Override
    public void onClick(View v) {
        int position=(Integer) v.getTag();
        Object object= getItem(position);
        DataModel dataModel=(DataModel)object;
    }

    private int lastPosition = -1;

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        DataModel dataModel = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        ViewHolder viewHolder; // view lookup cache stored in tag

        final View result;

        if (convertView == null) {
           viewHolder = new ViewHolder();
            LayoutInflater inflater = LayoutInflater.from(getContext());
            convertView = inflater.inflate(R.layout.lv_cues_row, parent, false);
            viewHolder.CueLabel = (TextView) convertView.findViewById(R.id.CueLabel);
            viewHolder.CueName = (TextView) convertView.findViewById(R.id.CueName);

            result=convertView;

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
            result=convertView;
        }

        viewHolder.CueLabel.setText(dataModel.getLAB());
        viewHolder.CueName.setText(dataModel.getNAME());

        return convertView;
    }

}

DataModel:

package it.rockopera.scsremote;

public class DataModel {

    String cueLABEL;
    String cueNAME;

    public DataModel(String cueL, String cueN ) {
        this.cueLABEL=cueL;
        this.cueNAME=cueN;
    }

    public String getLAB() {
        return cueLABEL;
    }

    public String getNAME() {
        return cueNAME ;
    }
}

DB Layer:

package it.rockopera.scsremote;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Looper;
import android.util.Log;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.HashMap;
import android.os.Handler;

public class DBLayer  {

    Context context;

    public static enum TipoQuery {
        Selezione,
        Comando
    }

    public static final String DATABASE_NAME = "scsDB";
    public static final int DATABASE_VERSION = 1;

    ArrayList<DataModel> dataModels;
    ListView listView;
    private static CustomAdapter adapter;

    private DbHelper ourHelper;
    private  static Context ourContext;
    private static SQLiteDatabase ourDatabase;

    private static class DbHelper extends SQLiteOpenHelper {

        public DbHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
            // TODO Auto-generated constructor stub
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE 'Cues_table' ('CueNUM' INTEGER, 'CueLABEL' TEXT, 'CueNAME' TEXT,
            'CueLEN' INTEGER, 'CuePOS' INTEGER, 'CueTYPE' TEXT, 'CueSTATE' INTEGER, 'CueColB' TEXT, 'CueColF' TEXT);");

            Log.e("DB tabella ", "creata");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            //db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLECN);
            //onCreate(db);
        }
    }

    public DBLayer(Context c){
        this.ourContext = c;
       // handler = null;
    }

    public DBLayer open() throws SQLException {
        this.ourHelper = new DbHelper(ourContext);
        this.ourDatabase = ourHelper.getWritableDatabase();
        return this;
    }

    public void close(){
        this.ourHelper.close();
    }

    public  void updateDB(String LAB, Integer STAT)
    {
        ourDatabase.execSQL("UPDATE Cues_table set CueSTATE = " + STAT + " WHERE CueLABEL = '" + LAB + "'" );

       // MainActivity main = new MainActivity(); // create new instance and set reference

    //    adapter.notifyDataSetChanged();

               // main.UpdateLV(); //Code goes here
            }

    public void deleteAll()
    {
        ourDatabase.execSQL("DELETE from Cues_table");
    }

    public Integer CountRecords()
    {
        Cursor cc = ourDatabase.rawQuery("SELECT * from Cues_table",null);
        int recCount = cc.getCount();
        return recCount;
    }

    public Cursor Execute(String Query, TipoQuery tipoCmd){
        Cursor c = null;

        try{
            switch(tipoCmd){
                case Comando:
                    ourDatabase.execSQL(Query);
                    break;
                case Selezione:
                    c = ourDatabase.rawQuery(Query,null);
                    break;
            }
        }catch (Exception e){}

        return c;
    }
}

In mainactivity I have this method to update LISTVIEW:

 public void UpdateLV(){

            try{
                DBLayer db = new DBLayer(context);
                db.open();
                CuesLV =(ListView)findViewById(R.id.listP);

                // PLAYING CUES

                dataModels= new ArrayList<>();

                String strQuery = "SELECT CueLABEL, CueNAME FROM Cues_table";
                Cursor c = db.Execute(strQuery, DBLayer.TipoQuery.Selezione);

                if (c != null){
                    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
                        dataModels.add(new DataModel(c.getString(0), c.getString(1)));
                    }
                }

                adapter= new CustomAdapter(dataModels,getApplicationContext());

               /* Log.e("prima di" , " NOTIFY");

                CuesLV.setAdapter(adapter);
                adapter.notifyDataSetChanged();

                Log.e("dopo di" , " NOTIFY");*/

      /*  listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                DataModel dataModel= dataModels.get(position);
 });
            }*/
            }catch (Exception e){}
        }
    }

When Database is updated (see DBLayer Class) I would like to refresh LISTVIEW in mainActivity view ...

I tried ... with no results ...

Thanks.

[simone giusti]

Liutauras Vilda wrote:Too difficult as for beginning. Moving to Java in General. This post will self dissapear in few days.

Maybe too difficult for me !!
thanks.

[simone giusti]

After updating DB values I run this:

 public void UPDLV(){


        adapter.notifyDataSetChanged();

    
    }

but nothing happens ...

[Giovanni Montano]

as for the other post, should be solved with CursorLoaders

simone giusti wrote:I am not able to update Listview when database is updated.

Custom Adapter

package it.rockopera.scsremote;

/**
 * Created by Simone on 10/12/2016.
 */

import android.content.Context;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.ArrayList;

/**
 * Created by anupamchugh on 09/02/16.
 */
public class CustomAdapter extends ArrayAdapter<DataModel> implements View.OnClickListener{

    private ArrayList<DataModel> dataSet;
    Context mContext;

    // View lookup cache
    private static class ViewHolder {
        TextView CueLabel;
        TextView CueName;
    }

    public CustomAdapter(ArrayList<DataModel> data, Context context) {
        super(context, R.layout.lv_cues_row, data);
        this.dataSet = data;
        this.mContext=context;
    }


    @Override
    public void onClick(View v) {
        int position=(Integer) v.getTag();
        Object object= getItem(position);
        DataModel dataModel=(DataModel)object;
    }

    private int lastPosition = -1;

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // Get the data item for this position
        DataModel dataModel = getItem(position);
        // Check if an existing view is being reused, otherwise inflate the view
        ViewHolder viewHolder; // view lookup cache stored in tag

        final View result;

        if (convertView == null) {
           viewHolder = new ViewHolder();
            LayoutInflater inflater = LayoutInflater.from(getContext());
            convertView = inflater.inflate(R.layout.lv_cues_row, parent, false);
            viewHolder.CueLabel = (TextView) convertView.findViewById(R.id.CueLabel);
            viewHolder.CueName = (TextView) convertView.findViewById(R.id.CueName);

            result=convertView;

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
            result=convertView;
        }

        viewHolder.CueLabel.setText(dataModel.getLAB());
        viewHolder.CueName.setText(dataModel.getNAME());

        return convertView;
    }

}

DataModel:

package it.rockopera.scsremote;

public class DataModel {

    String cueLABEL;
    String cueNAME;

    public DataModel(String cueL, String cueN ) {
        this.cueLABEL=cueL;
        this.cueNAME=cueN;
    }

    public String getLAB() {
        return cueLABEL;
    }

    public String getNAME() {
        return cueNAME ;
    }
}

DB Layer:

package it.rockopera.scsremote;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Looper;
import android.util.Log;
import android.widget.ListView;

import java.util.ArrayList;
import java.util.HashMap;
import android.os.Handler;

public class DBLayer  {

    Context context;

    public static enum TipoQuery {
        Selezione,
        Comando
    }

    public static final String DATABASE_NAME = "scsDB";
    public static final int DATABASE_VERSION = 1;

    ArrayList<DataModel> dataModels;
    ListView listView;
    private static CustomAdapter adapter;

    private DbHelper ourHelper;
    private  static Context ourContext;
    private static SQLiteDatabase ourDatabase;

    private static class DbHelper extends SQLiteOpenHelper {

        public DbHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
            // TODO Auto-generated constructor stub
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE 'Cues_table' ('CueNUM' INTEGER, 'CueLABEL' TEXT, 'CueNAME' TEXT,
            'CueLEN' INTEGER, 'CuePOS' INTEGER, 'CueTYPE' TEXT, 'CueSTATE' INTEGER, 'CueColB' TEXT, 'CueColF' TEXT);");

            Log.e("DB tabella ", "creata");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            //db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLECN);
            //onCreate(db);
        }
    }

    public DBLayer(Context c){
        this.ourContext = c;
       // handler = null;
    }

    public DBLayer open() throws SQLException {
        this.ourHelper = new DbHelper(ourContext);
        this.ourDatabase = ourHelper.getWritableDatabase();
        return this;
    }

    public void close(){
        this.ourHelper.close();
    }

    public  void updateDB(String LAB, Integer STAT)
    {
        ourDatabase.execSQL("UPDATE Cues_table set CueSTATE = " + STAT + " WHERE CueLABEL = '" + LAB + "'" );

       // MainActivity main = new MainActivity(); // create new instance and set reference

    //    adapter.notifyDataSetChanged();

               // main.UpdateLV(); //Code goes here
            }

    public void deleteAll()
    {
        ourDatabase.execSQL("DELETE from Cues_table");
    }

    public Integer CountRecords()
    {
        Cursor cc = ourDatabase.rawQuery("SELECT * from Cues_table",null);
        int recCount = cc.getCount();
        return recCount;
    }

    public Cursor Execute(String Query, TipoQuery tipoCmd){
        Cursor c = null;

        try{
            switch(tipoCmd){
                case Comando:
                    ourDatabase.execSQL(Query);
                    break;
                case Selezione:
                    c = ourDatabase.rawQuery(Query,null);
                    break;
            }
        }catch (Exception e){}

        return c;
    }
}

In mainactivity I have this method to update LISTVIEW:

 public void UpdateLV(){

            try{
                DBLayer db = new DBLayer(context);
                db.open();
                CuesLV =(ListView)findViewById(R.id.listP);

                // PLAYING CUES

                dataModels= new ArrayList<>();

                String strQuery = "SELECT CueLABEL, CueNAME FROM Cues_table";
                Cursor c = db.Execute(strQuery, DBLayer.TipoQuery.Selezione);

                if (c != null){
                    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()){
                        dataModels.add(new DataModel(c.getString(0), c.getString(1)));
                    }
                }

                adapter= new CustomAdapter(dataModels,getApplicationContext());

               /* Log.e("prima di" , " NOTIFY");

                CuesLV.setAdapter(adapter);
                adapter.notifyDataSetChanged();

                Log.e("dopo di" , " NOTIFY");*/

      /*  listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                DataModel dataModel= dataModels.get(position);
 });
            }*/
            }catch (Exception e){}
        }
    }

When Database is updated (see DBLayer Class) I would like to refresh LISTVIEW in mainActivity view ...

I tried ... with no results ...

Thanks.

[simone giusti]

Giovanni Montano wrote:as for the other post, should be solved with CursorLoaders

simone giusti wrote:

Maybe this is too difficult for me ...

I find a loto of examples suggesting to use notifyDataSetChanged but it has no effect. Maybe I choose the wrong place to put it.

Any suggestions ?

[Ron McLeod]

One solution would be to have the ListAdapter register a listener with the data source so that whenever the data source is modified, it would call the listener, and the listener would then call the notifyDataSetChanged method.  For example:

import java.util.List;
import android.content.Context;
import android.widget.ArrayAdapter;

public class DBListAdapter extends ArrayAdapter<String> implements DBWatcher {
	private WatchableDBHelper dbHelper;
	private List<String> itemsCache;

	public DBListAdapter(Context context, int resource) {
		super(context, resource);
		dbHelper = new WatchableDBHelper(context,
				WatchableDBHelper.DATABASE_NAME, null,
				WatchableDBHelper.VERSION);
		itemsCache = dbHelper.getItems();
		dbHelper.setWatcher(this);
	}

	@Override
	public String getItem(int position) {
		System.out.println("getItem: " + position);
		return itemsCache.get(position);
	}

	@Override
	public int getCount() {
		return itemsCache.size();
	}

	@Override
	public void onChange() {
		itemsCache = dbHelper.getItems();
		notifyDataSetChanged();
	}
}

import java.util.ArrayList;
import java.util.List;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class WatchableDBHelper extends SQLiteOpenHelper {
	public static final String DATABASE_NAME = "Test.db";
	public static final String TABLE_NAME = "Items";
	public static final String COLUMN_ITEM_NAME = "item_name";
	public static final int VERSION = 1;
	
	private DBWatcher watcher = null;
	private String[] initialItems = { "Apple", "Banana", "Cherry", "Date" };

	public WatchableDBHelper(Context context, String name, CursorFactory factory,
			int version) {
		super(context, DATABASE_NAME, factory, version);
	}

	@Override
	public void onCreate(SQLiteDatabase sqlDB) {
		sqlDB.execSQL("CREATE TABLE " + TABLE_NAME + " (" + COLUMN_ITEM_NAME
				+ " TEXT)");
		for (String item : initialItems) {
			addItem(sqlDB, item);
		}
	}

	@Override
	public void onUpgrade(SQLiteDatabase sqlDB, int i, int i1) {
		sqlDB.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
		onCreate(sqlDB);
	}

	public void setWatcher(DBWatcher watcher) {
		this.watcher = watcher;
	}

	public List<String> getItems() {
		List<String> items = new ArrayList<String>();
		SQLiteDatabase db = getReadableDatabase();
		Cursor c = db.rawQuery("SELECT " + COLUMN_ITEM_NAME + " FROM "
				+ TABLE_NAME, null);

		c.moveToFirst();
		while (!c.isAfterLast()) {
			String item = c.getString(c.getColumnIndex(COLUMN_ITEM_NAME));
			System.out.println(item);
			items.add(item);
			c.moveToNext();
		}
		return items;
	}

	public void addItem(String item) {
		SQLiteDatabase db = getWritableDatabase();
		addItem(db, item);
	}

	private void addItem(SQLiteDatabase db, String item) {
		ContentValues cValues = new ContentValues();
		cValues.put(COLUMN_ITEM_NAME, item);
		db.insert(TABLE_NAME, null, cValues);
		notifyChangeWatcher();
	}

	public void removeItem(String item) {
		SQLiteDatabase db = getWritableDatabase();
		db.delete(TABLE_NAME, COLUMN_ITEM_NAME + "=?", new String[] { item });
		notifyChangeWatcher();
	}

	private void notifyChangeWatcher() {
		if (watcher != null) {
			watcher.onChange();
		}
	}
}

public interface DBWatcher {
	void onChange();
}

[simone giusti]

Ron McLeod wrote:One solution would be to have the ListAdapter register a listener with the data source so that whenever the data source is modified, it would call the listener, and the listener would then call the notifyDataSetChanged method.  For example:

Thanks Ron,
what I did not understand is why I can't simply call notifyDataSetChanged once db is updated to refresh listview.

    public void UPDLV(){

           adapter.notifyDataSetChanged();

    }

DB is updated in DBhelper.class

    public  void updateDB(String LAB, Integer STAT)
    {

       ourDatabase.execSQL("UPDATE Cues_table set CueSTATE = " + STAT + " WHERE CueLABEL = '" + LAB + "'" );
        Log.e("UPDATE DB ", LAB + " state: " + STAT);

       new PostTask().execute();



....

// ASYNC task calling UPDLV in main activity

 private class PostTask extends AsyncTask<String, Integer, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
           


        }

        @Override
        protected String doInBackground(String... params) {
            // DO IN BACKGROUND
          
            return "All Done!";

        }



        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            Log.e("POST ", "EXECUTE");
            MainActivity main = new MainActivity();
            main.UPDLV();
            // POST EXECUTE
        }
    }



    }

Thanks

[Ron McLeod]

One problem is the you are calling your update method on a new instance of MainActivity, rather than the launched MainActivity instance:

MainActivity main = new MainActivity();
main.UPDLV();

If you want to involve the MainActivity in updating the list view, then pass AsyncTask a reference to use to inform the MainActivity that the list data set has changed.  Here's an example:

import android.app.ListActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;

public class MainActivity extends ListActivity implements ListUpdateListener {
	private DBListAdapter listAdapter;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		listAdapter = new DBListAdapter(this, R.layout.activity_main);
		setListAdapter(listAdapter);
		
		// click anywhere on the list to asynchronously add an item
		getListView().setOnItemClickListener(new OnItemClickListener() {
			@Override
			public void onItemClick(AdapterView<?> parent, View view,
					int position, long id) {
				AddToListParams params = new AddToListParams();
				params.item = "Frankenberry";
				params.listAdapter = listAdapter;
				params.listUpdateListener = MainActivity.this;
				new AddToListTask().execute(params);
			}
		});
	}

	@Override
	public void onListDataUpdated() {
		// inform adapter that list data has changed
		listAdapter.notifyDataSetChanged();
	}
}

class AddToListParams {
	String item;
	DBListAdapter listAdapter;
	ListUpdateListener listUpdateListener;
}

class AddToListTask extends
		AsyncTask<AddToListParams, Void, ListUpdateListener> {

	@Override
	protected ListUpdateListener doInBackground(AddToListParams... params) {
		// change list data
		params[0].listAdapter.addItem(params[0].item);
		
		// returned listener reference passed to onPostExecute method
		return params[0].listUpdateListener;
	}

	@Override
	protected void onPostExecute(ListUpdateListener listener) {
		// inform MainActivity that list data has changed  
		listener.onListDataUpdated();
	}
}

public interface ListUpdateListener {
	void onListDataUpdated();
}

[simone giusti]

Ron McLeod wrote:One problem is the you are calling your update method on a new instance of MainActivity, rather than the launched MainActivity instance:

MainActivity main = new MainActivity();
main.UPDLV();

Thank Ron ... helpful !!