Android SQLite - small I/O difficulty
public class DBExampleActivity extends Activity implements OnClickListener{


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Declare the database object and open.
    MyDBManager db = new MyDBManager(this);
    db.open();

    // Take names from EditTexts and store in string.
    first_name  = fname.getText().toString();
    last_name   = lname.getText().toString();
}

@Override
public void onClick(View view) {
    // In the onclick method, add values to database, call next activity
    db.insertData(first_name, last_name);
    Intent intent = new Intent(this, Display.class);
    startActivity(intent);
}}

public class Display extends Activity {

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    Cursor myCursor = db.getDetails();

    // Get relevant data from columns in cursor.
    username =  c.getString(c.getColumnIndex("first_name"));
    password =  c.getString(c.getColumnIndex("last_name"));

    // set textview values.
    fname.setText(first_name);
    lname.setText(last_name);
}}

public class MyDBManager {
public static final String KEY_ROWID = "id";
public static final String KEY_USERNAME = "firstname";
public static final String KEY_PASSWORD = "lastname";

private static final String DATABASE_NAME = "User_Information";
private static final String DATABASE_TABLE = "User_name";
private static final int DATABASE_VERSION = 1;

private static final String DATABASE_CREATE =
                    "create table " + DATABASE_TABLE +
                    " (_id integer primary key autoincrement, " +
                    "username text not null, " +
                    "password text not null); "  ;

private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;


public MyDBManager(Context context){
    this.context = context;
    DBHelper = new DatabaseHelper(context);
}

private static class DatabaseHelper extends SQLiteOpenHelper{

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

    // Creates the database
    @Override
    public void onCreate(SQLiteDatabase db){
        db.execSQL(DATABASE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion){
        // on triggered if the database version has increased.
        // used if you want to change structure of column: eg add new column.
    }
} // end helper class



// Methods used to access and change data in DB:
public MyDBManager open() throws SQLException{
    db = DBHelper.getWritableDatabase();
    return this;
}


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

public long insertData(String username, String password){
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_USERNAME, username);
    initialValues.put(KEY_PASSWORD, password);

    return db.insert(DATABASE_TABLE, null, initialValues);
}


public Cursor getDetails(long rowId){
    Cursor c = db.query(true, DATABASE_TABLE, new String[]{
                    KEY_ROWID,
                    KEY_USERNAME,
                    KEY_PASSWORD},
                    KEY_ROWID + "=" + rowId,
                    null,
                    null,
                    null,
                    null,
                    null);

    if(c != null){
        c.moveToFirst();
    }
    return c;
}}// End myDBManager Class.

TextView fname = (TextView) findViewById(R.id.mytextview1);
TextView lname = (TextView) findViewById(R.id.mytextview2);
 // set textview values.
    fname.setText(first_name);
    lname.setText(last_name);