Bdtjtk

I'm creating a normal android application in which I'm trying to fetch data using Sqlite database but the values is not being retrieved please tell me where I'm going wrong?

activity_main.xml

   <Button

        android:id="@+id/button_viewAll"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="View Details"

               />

DatabaseHelper Class

   public static final String DATABASE_NAME = "Gym.db";

   public static final String TABLE_NAME = "Exercise";

   public static final String COL_1 = "exercise_id";

   public static final String COL_2 = "exercise_name";

   public static final String COL_3 = "body_part";

   public static final String COL_4 = "description";



    public DatabaseHelper( Context context) {

    super(context, DATABASE_NAME, null, 1);

}



@Override

public void onCreate(SQLiteDatabase db) {



    db.execSQL("create table " + TABLE_NAME +" (exercise_id INTEGER PRIMARY KEY AUTOINCREMENT,exercise_name TEXT,body_part TEXT,description TEXT)");

}



@Override

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

    db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);

    onCreate(db);

}

public Cursor getAllData() {

    SQLiteDatabase db = this.getWritableDatabase();

    Cursor res = db.rawQuery("select * from "+TABLE_NAME, null);

    return res;

}

}

MainActivity.java

 public class MainActivity extends AppCompatActivity {

   DatabaseHelper myDb;

   Button texercise_id, texercise_name, tbody_part, tdescription;



Button btnviewAll;

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    myDb = new DatabaseHelper(this);



    texercise_id = (Button)findViewById(R.id.button_viewAll);

    texercise_name = (Button)findViewById(R.id.button_viewAll);

    tbody_part = (Button)findViewById(R.id.button_viewAll);

    tdescription = (Button)findViewById(R.id.button_viewAll);

    btnviewAll = (Button)findViewById(R.id.button_viewAll);

    viewAll();

}

public void viewAll() {

    btnviewAll.setOnClickListener(

            new View.OnClickListener() {

                @Override

                public void onClick(View v) {



                    Cursor res = myDb.getAllData();

                    if(res.getCount() == 1) {

                        // show message

                        showMessage("Error","Nothing found");

                        return;

                    }



                    StringBuffer buffer = new StringBuffer();

                    while (res.moveToNext()) {

                        buffer.append("exercise_id :"+ res.getString(0)+"n");

                        buffer.append("exercise_name :"+ res.getString(1)+"n");

                        buffer.append("body_part :"+ res.getString(2)+"n");

                        buffer.append("description :"+ res.getString(3)+"nn");

                    }



                    // Show all data

                    showMessage("Data Found",buffer.toString());

                }

            }

    );

}

public void showMessage(String title,String Message){

    AlertDialog.Builder builder = new AlertDialog.Builder(this);

    builder.setCancelable(true);

    builder.setTitle(title);

    builder.setMessage(Message);

    builder.show();

}





}

I've tried this before also but this same issue I'm facing with retrieving data from SQLite Database.

From your code it appears that all is working fine. However, there does not appear to be any data added, nor a means to add data. Thus the dialog is showing no data BUT it is not showing the message that indicates no data.

1. Fix the dialog to indicate no data

To fix the Dialog showing no data you need to check to see if the Cursor has not rows rather than 1 row. So change the line :-

if(res.getCount() == 1) { 

to be

if(res.getCount() < 1) {

2. Add some data so data is displayed

To show some data you need to add some data. To add some data you could have a method, in the DatabaseHelper class that allows data to be added. For example :-

public long addData(String excercise_name, String body_part, String description) {

    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues cv = new ContentValues();

    cv.put(COL_2,excercise_name);

    cv.put(COL_3,body_part);

    cv.put(COL_4,body_part);

    return db.insert(TABLE_NAME,null,cv);

}

You would then need to actually add some data, as an example of doing so, the following method could be added to your MainActivity :-

private void addSomeDataButOnlyIfNoneExists() {

    if (DatabaseUtils.queryNumEntries(myDb.getWritableDatabase(),DatabaseHelper.TABLE_NAME) < 1) {

        myDb.addData("Squat","Legs","Squat");

        myDb.addData("Push up","Arms","Push up");

        myDb.addData("Run","Legs and Arms","Rapidly put one foot in front of the other");

    }

}

• Note this will just add the above data once (the first line is checking to see if data already exists).

You could invoke the method using :-

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);

    myDb = new DatabaseHelper(this);

    addSomeDataButOnlyIfNoneExists(); //<<<<<<<<<< ADDED



   ........ rest of your code

Result (with data)

using the above, running the app and clicking on the View Details button results in :-