I have a gridview class here:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://ift.tt/nIICcg"
xmlns:tools="http://ift.tt/LrGmb4"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorPrimaryDark"
tools:context=".MainActivity">
<LinearLayout
android:id="@+id/topContent"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="7">
<TextView
android:id="@+id/textView0"
android:background="@color/white"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="ID: "
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
<TextView
android:id="@+id/textView1"
android:background="@color/purple"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/gridCode"
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
<TextView
android:id="@+id/textView2"
android:background="@color/green"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/gridDay"
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
<TextView
android:id="@+id/textView3"
android:background="@color/orange"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/gridStart"
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
<TextView
android:id="@+id/textView4"
android:background="@color/blue"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/gridDuration"
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
<TextView
android:id="@+id/textView5"
android:background="@color/yellow"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/gridType"
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
<TextView
android:id="@+id/textView6"
android:background="@color/red"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="@string/gridRoom"
android:textSize="18sp"
android:textColor="@color/black"
android:gravity="center"
/>
</LinearLayout>
<GridView
android:id="@+id/gridTable"
android:layout_below="@+id/topContent"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:horizontalSpacing="10dip"
android:verticalSpacing="15dip"
android:stretchMode="columnWidth"
android:gravity="center"
android:numColumns="7"
android:background="@color/colorPrimary"
android:textSize="14sp"
>
</GridView>
</RelativeLayout>
and a database helper:
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper
{
//database information
public static final String DATABASE_NAME = "timetable.db";
public static final String TABLE_NAME = "timetable_data";
//the data each column will store
public static final String COL_1 = "ID";
public static final String COL_2 = "CODE";
public static final String COL_3 = "DAY";
public static final String COL_4 = "START";
public static final String COL_5 = "DURATION";
public static final String COL_6 = "TYPE";
public static final String COL_7 = "ROOM";
//construct the database
public DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL("create table " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT,CODE TEXT,DAY TEXT,START TEXT,DURATION TEXT,TYPE TEXT,ROOM TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
onCreate(db);
}
public boolean insertData(String code, String day, String start, String duration, String type, String room)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_2,code);
contentValues.put(COL_3,day);
contentValues.put(COL_4,start);
contentValues.put(COL_5,duration);
contentValues.put(COL_6,type);
contentValues.put(COL_7, room);
long result = db.insert(TABLE_NAME,null,contentValues);
if(result == -1)
return false;
else
return true;
}
public Cursor getAllData()
{
SQLiteDatabase db = this.getWritableDatabase();
Cursor data = db.rawQuery("select * from "+TABLE_NAME,null);
return data;
}
public Integer deleteEntry(String id)
{
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(TABLE_NAME,"ID = ?", new String [] {id});
}
}
I'm trying to populate this gridview with data stored in the database, everything compiles fine, but in the app i get an error saying that data from Col-1 (the id column) cannot be retrieved.
this is the gridviewactivity.java class mentioned in the above code:
import android.database.Cursor;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.GridView;
import android.widget.Toast;
import java.util.ArrayList;
/**
* Created by natha on 17/02/2016.
*
* This class gets all of the information in the getAllData() method, adds it to an array list,
* then an array adapter reads the data from this array list and applies that data to the GridView.
*
*/
public class GridViewActivity extends MainActivity
{
private GridView gridTable;
private ArrayList<String> moduleList;
private ArrayAdapter<String> adapter;
private Cursor data;
DatabaseHelper timetableDB;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState); setContentView(R.layout.gridview);
//GridView
gridTable=(GridView) findViewById(R.id.gridTable);
//ArrayList
moduleList = new ArrayList<>();
adapter = new ArrayAdapter<>(getApplicationContext(),
android.R.layout.simple_spinner_item,moduleList);
String id, code, day, time, duration, type, room;
id = "";
code = "";
day = "";
time = "";
duration = "";
type = "";
room = "";
timetableDB = new DatabaseHelper(getBaseContext());//getting the context object
timetableDB.getAllData();
try
{
//for holding retrieve data from query and store in the form of rows
Cursor data=timetableDB.getAllData();
//Move the cursor to the first row.
if(data.moveToFirst())
{
do
{
id = data.getString(data.getColumnIndex ("id"));
code = data.getString(data.getColumnIndex ("code"));
day = data.getString(data.getColumnIndex ("day"));
time = data.getString(data.getColumnIndex ("time"));
duration = data.getString(data.getColumnIndex ("duration"));
type = data.getString(data.getColumnIndex ("type"));
room = data.getString(data.getColumnIndex ("room"));
//add in to array list
moduleList . add(id);
moduleList . add(code);
moduleList . add(day);
moduleList . add(time);
moduleList . add(duration);
moduleList . add(type);
moduleList . add(room);
gridTable.setAdapter(adapter);
}
while(data.moveToNext());//Move the cursor to the next row.
}
else
{
Toast.makeText(getApplicationContext(),
"No data found", Toast.LENGTH_LONG).show();
}
}catch(Exception e)
{
Toast.makeText(getApplicationContext(),
"No data found "+e.getMessage(), Toast.LENGTH_LONG).show();
}
timetableDB.close();
}
}
am i using the cursor correctly in this class?
thanks!
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