sqlite row ids not matching listview - ANDROID

问题

This may turn out as a lame question, but I am a beginner and don't seem to understand the behavior of my app.

I have a SQLite data base, and a list view in the main activity. In the list view I display the List no.(row id) and other details. and on pressing the list item, a new activity opens up which displays the details in a textview and has 2 image buttons for delete and sync.

The app works just fine until I delete any entry.

Once I delete any entry the row id on the listview doesn't seem to update the row number. (if i delete the first row, the row on top shows 2(should be 1, as it is the new first row)).

However when I display the details of record it comes out correct. (the second item on the list show the row number 2)

Also when I press press an item in the list view whose position is same as the position i have deleted earlier the app crashes(Suppose i delete the first entry, after that whenever I click on the first Item on the list view to display it the app crashes)

Error I get on app crash :

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aakashmaroti.fillup/com.example.aakashmaroti.fillup.DisplayDetails}: android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0

My main activity

package com.example.aakashmaroti.fillup;

import android.app.Dialog;
import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.database.Cursor;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;


public class StartScreen extends ActionBarActivity implements View.OnClickListener {


    FavoriteList favList = new FavoriteList();

    TextView rid,ts,sd;
    ListView lv;
    Context context=this;
    Find db=new Find(this);
    List<FavoriteList> favoriteList;
    LinearLayout layout;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_start_screen);
        Button b = (Button) findViewById(R.id.AddButton);
        b.setOnClickListener(this);
        lv = (ListView) findViewById(R.id.listview);
        try
        {
            populateListViewFromDatabase();
        } catch (Exception e)
        {
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
            e.printStackTrace();
        }

        lv.setOnItemClickListener(new AdapterView.OnItemClickListener()
        {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id)
            {
                showsDialog(position);
            }
        });


    }


    @Override
    public void onResume()
    {
        super.onResume();
        try
        {
            populateListViewFromDatabase();
        } catch (Exception e)
        {
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
            e.printStackTrace();
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_start_screen, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onClick(View v) {

        switch (v.getId())
        {
            case R.id.AddButton:
                startActivity(new Intent(this,Form.class));
                break;

            default: break;
        }
    }

    public void populateListViewFromDatabase()throws Exception
    {
        Find info=new Find(this);
        try
        {
            info.open();
            SimpleCursorAdapter myCursorAdapter;
            myCursorAdapter = info.listUp();
            lv.setAdapter(myCursorAdapter);
            info.close();

        } catch (SQLException e)
        {
            e.printStackTrace();
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
        }
    }
    public void showsDialog(int pos)
    {

        pos++;
        String s = "";
        s += pos;
        Intent i = new Intent(getApplicationContext(), DisplayDetails.class);
        i.putExtra("position", s);
        startActivity(i);

        try
        {
            populateListViewFromDatabase();
        } catch (Exception e)
        {
            e.printStackTrace();
        }
    }

}

The sqlite data base managing class

package com.example.aakashmaroti.fillup;

import android.app.Dialog;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by Aakash Maroti on 28-Dec-14.
 */
public class Find
{
    public static final String KEY_ROWID = "_id";
    public static final String KEY_TIMESTAMP= "time_stamp";
    public static final String KEY_IS_SYNCED = "sync";
    public static final String KEY_NameOfCompany="name_of_company";



    private static final String DATABASE_NAME = "FillUpFormsDB";
    private static final String DATABASE_TABLE = "FillUpFormsTable";
    private static final int DATABASE_VERSION = 1;

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




    private static class DbHelper extends SQLiteOpenHelper
    {

        public DbHelper(Context context)
        {
            super(context,DATABASE_NAME,null,DATABASE_VERSION);
        }



        @Override
        public void onCreate(SQLiteDatabase db)
        {
            db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
                    KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                            KEY_IS_SYNCED +" TEXT NOT NULL, " +
                            KEY_TIMESTAMP +" TEXT NOT NULL, " +
                            KEY_NameOfCompany+" TEXT NOT NULL);"
            );
        }

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

    }  


    public Find(Context c)
    {
        ourContext = c;
    }

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

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


    public long createEntry(String isSynced, String timeStamp, String nameOfCompany)
    {
        ContentValues cv=new ContentValues();
        cv.put(KEY_IS_SYNCED,isSynced);
        cv.put(KEY_TIMESTAMP,timeStamp);
        cv.put(KEY_NameOfCompany,nameOfCompany);        

        return ourDatabase.insert(DATABASE_TABLE,null,cv);

    }

    public SimpleCursorAdapter listUp()
    {

        String columns[]=new String[]{KEY_ROWID,KEY_TIMESTAMP,KEY_IS_SYNCED};
        Cursor c= ourDatabase.query(DATABASE_TABLE,columns,null,null,null,null,null);
        int toViewIDs[] = new int[]{R.id.rowno,R.id.timestamp,R.id.syncdetails};
        SimpleCursorAdapter CursorAdapter;
        CursorAdapter = new SimpleCursorAdapter(ourContext,R.layout.design_row,c,columns,toViewIDs,0);
        return CursorAdapter;
    }

    public String getDetails(long row)
    {
        String columns[]=new String[] {KEY_ROWID, KEY_IS_SYNCED, KEY_TIMESTAMP,KEY_NameOfCompany};
        String result="";        
        Cursor c= ourDatabase.query(DATABASE_TABLE,columns,KEY_ROWID+"="+row,null,null,null,null);
        if(c!=null)
        {
            String r;
            c.moveToFirst();
            r="\nRecord No. : "+c.getString(0)+"\n\nSync Status:"+c.getString(1)+"\n\nTime of Creation:\n"+c.getString(2)+"\n\nName of Company:\n"+c.getString(3);
            return r;
        }

        return result;
    }

    public void DeleteRow(int pos)
    {
        ourDatabase.delete(DATABASE_TABLE,KEY_ROWID+"="+pos,null);
    }
}

the class for the new activity that shows the result.

package com.example.aakashmaroti.fillup;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageButton;
import android.widget.TextView;
import android.widget.Toast;

import java.sql.SQLException;


public class DisplayDetails extends ActionBarActivity implements View.OnClickListener

{

    ImageButton ibSync;
    ImageButton ibDelete;
    TextView DispDetails;
    int pos;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        Bundle extras = getIntent().getExtras();

        String value="1";
        if (extras != null) {
           value = extras.getString("position");
        }
        pos=Integer.parseInt(value);
        setContentView(R.layout.activity_display_details);
        ibSync=(ImageButton)findViewById(R.id.imageButtonSync);
        ibDelete=(ImageButton)findViewById(R.id.imageButtonDelete);
        DispDetails = (TextView)findViewById(R.id.textViewDisplayDetails);
        String s="";

        ibSync.setOnClickListener(this);
        ibDelete.setOnClickListener(this);

        Find info1=new Find(this);
        try
        {
            info1.open();
            s=info1.getDetails(pos);
            info1.close();

        } catch (SQLException e)
        {
            e.printStackTrace();
            Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
        }
        DispDetails.setText(s);

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_display_details, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item)
    {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings)
        {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onClick(View v)
    {
        if(v.getId()==R.id.imageButtonSync)
        {
            Toast.makeText(getApplicationContext(), "This functionality has not yet been added", Toast.LENGTH_LONG).show();
        }
        if(v.getId()==R.id.imageButtonDelete)
        {   Find info1=new Find(this);
            try
            {
                info1.open();
                info1.DeleteRow(pos);
                info1.close();

            } catch (SQLException e)
            {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(), "Oops there has been an error "+e.toString()+"", Toast.LENGTH_LONG).show();
            }


            Toast.makeText(getApplicationContext(), "This record has been successfully deleted", Toast.LENGTH_LONG).show();
            cancel();
        }
    }

    public void cancel()
    {
        this.finish();
        return;
    }
}

Xml file of a single row in the listview

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent">


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:text=""
        android:textStyle="bold"
        android:clickable="true"
        android:id="@+id/rowno"/>   

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:text=""
        android:clickable="true"
        android:id="@+id/timestamp"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:textStyle="bold"
        android:text=""
        android:clickable="true"
        android:id="@+id/syncdetails"/>

</LinearLayout>

Any help will be greatly appreciated.

Thanks in advance.

回答1:

Its because you are passing the list view item position, it should be the database row id.

Change

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
    showsDialog(position);
}

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
    TextView pos = (TextView) view.findViewById(R.id.rowno);
    showsDialog(pos.getText().toString());
}

Also you said

Once I delete any entry the row id on the listview doesn't seem to update the row number. (if i delete the first row, the row on top shows 2(should be 1, as it is the new first row)).

But it wouldn't because this is the database row id not the list view position.