mardi 29 septembre 2015

SimpleCursorAdapter to get Data from Database to ListView

I got the app to create a database and I'm able to create new entries, however, I don't know, how to read the database to get the stored data in a ListView.

public class DatabaseHelper extends SQLiteOpenHelper {

private static final String DATABASE_NAME="students.db";
private static final String TABLE_NAME="student_details";
private static final String COL_1="ID";
private static final String COL_2="NAME";
private static final String COL_3="SURNAME";
private static final String COL_4="MARKS";
private static final int DATABASE_VERSION=1;

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

}



@Override
public void onCreate(SQLiteDatabase db) {


db.execSQL("create table " + TABLE_NAME + "(ID INTEGER PRIMARY KEY AUTOINCREMENT,NAME TEXT,SURNAME TEXT,MARKS INTEGER)");

    Log.d("info", "TABLE WAS CREATED");


}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    db.execSQL("DROP TABLE IF EXIST " + TABLE_NAME);
    onCreate(db);
    Log.d("Info","TABLE WAS UPDATED");

}

public boolean insertdata(String name,String surname,String marks)
{

    SQLiteDatabase db= this.getWritableDatabase();

    ContentValues contentValues= new ContentValues();
    contentValues.put(COL_2,name);
    contentValues.put(COL_3, surname);
    contentValues.put(COL_4, marks);

    long result=db.insert(TABLE_NAME,null,contentValues);
    if (result==-1)
        return false;
    else
        return true;

}
public Cursor getallData()
{
    SQLiteDatabase db= this.getWritableDatabase();

    Cursor res=db.rawQuery("SELECT * FROM "+TABLE_NAME,null);
    return res;

}
public boolean updateData(String id,String name,String surname,String marks) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues contentValues = new ContentValues();
   // contentValues.put(COL_1, id);
           contentValues.put(COL_2, name);
    contentValues.put(COL_3, surname);
    contentValues.put(COL_4, marks);

    db.update(TABLE_NAME, contentValues, COL_1 + " =? ", new String[]{id});
    return true;

}
public Cursor getData(int id){
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res =  db.rawQuery( "select * from student_details where ID="+id+"", null );
    if(res != null && res.moveToFirst()) {
        return res;
    }
    return res;
}
public int deleteData(String id)
{
    SQLiteDatabase db = this.getWritableDatabase();
    return db.delete(TABLE_NAME, COL_1 + " =?", new String[]{id});

}
09-29 17:05:23.574  23469-23469/com.example.ky.studentmarks E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.aeiltech.studentmarks, PID: 23469
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ky.studentmarks/com.example.aeiltech.studentmarks.DisplayData}: java.lang.IllegalArgumentException: column '_id' does not exist
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2436)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2498)
        at android.app.ActivityThread.access$900(ActivityThread.java:179)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1324)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:146)
        at android.app.ActivityThread.main(ActivityThread.java:5641)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1288)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1104)
        at dalvik.system.NativeStart.main(Native Method)

enter code here public class DisplayData extends Activity {

DatabaseHelper myDB;
ListView list;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.data_display);
    list= (ListView) findViewById(R.id.listView);
    myDB= new DatabaseHelper(this);
    //Cursor res = myDB.getallData();
    String[] from={"ID","NAME","SURNAME","MARKS"};

    int[] to={R.id.textView11,R.id.textView13,R.id.textView15 };
    Cursor cursor=myDB.getallData();
   // allData();
    SimpleCursorAdapter adapter= new SimpleCursorAdapter(this,R.layout.custom_data_display,cursor,from,to);
    list.setAdapter(adapter);
    // adapter= new ArrayAdapter(this,R.layout.custom_data_display,)


}

enter code here

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