load from spinner sqlite with text and value

问题:

i have a spinner load data to sqlite

i have field id and field name in database.

private void loadSpinnerDataHama() {
        // database handler
        DatabaseSpinner db = new DatabaseSpinner(getApplicationContext()); 
        // Spinner Drop down elements
        List<String> lables = db.getAllLabels();
        // Creating adapter for spinner
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
        android.R.layout.simple_spinner_item, lables);
        // Drop down layout style - list view with radio button
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // attaching data adapter to spinner
        spin2.setAdapter(dataAdapter);
    }

    public List<String> getAllLabels(){
    List<String> labels = new ArrayList<String>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_LABELS;

    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            labels.add(cursor.getString(1));
        } while (cursor.moveToNext());
    }

    // closing connection
    cursor.close();
    db.close();

    // returning lables
    return labels;
}

and the result is

USA -> value is "USA"

France -> value is "France"

when i change the code labels.add(cursor.getString(1)); to labels.add(cursor.getString(0));

and the result is

1 -> value is "1"

2 -> value is "2"

i try with int position2 = spin2.getSelectedItemPosition()+1; but the value is id/position of spinner , not the id of database.

how to display field name on spinner. but the value is id of name

Example: The spinner display:

USA -> value is "1"

France -> value is "2"

BR

Alex

回答1:

It is really simple, what you can do is to implement/ represent what you need by a class, in the following manner :

Create the following class : SpinnerObject

public class SpinnerObject {

    private  int databaseId;
    private String databaseValue;

    public SpinnerObject ( int databaseId , String databaseValue ) {
        this.databaseId = databaseId;
        this.databaseValue = databaseValue;
    }

    public int getId () {
        return databaseId;
    }

    public String getValue () {
        return databaseValue;
    }

    @Override
    public String toString () {
        return databaseValue;
    }

}

Using this class, you can still use the Android implementation of the ArrayAdapter (no need to implement your own, since the toString method provides the string value that you want to display, and you still store the database id that you also need).

Now you will have to create your list as follows :

public List < SpinnerObject> getAllLabels(){
    List < SpinnerObject > labels = new ArrayList < SpinnerObject > ();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_LABELS;

    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if ( cursor.moveToFirst () ) {
        do {
            labels.add ( new SpinnerObject ( cursor.getString(0) , cursor.getString(1) ) );
        } while (cursor.moveToNext());
    }

    // closing connection
    cursor.close();
    db.close();

    // returning labels
    return labels;
}

Now that you have the list of objects with the values and ids, you load the spinner this way :

private void loadSpinnerDataHama() {
    // database handler
    DatabaseSpinner db = new DatabaseSpinner(getApplicationContext()); 
    // Spinner Drop down elements
    List <SpinnerObject> lables = db.getAllLabels();
    // Creating adapter for spinner
    ArrayAdapter<SpinnerObject> dataAdapter = new ArrayAdapter<SpinnerObject>(this,
    android.R.layout.simple_spinner_item, lables);
    // Drop down layout style - list view with radio button
    dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    // attaching data adapter to spinner
    spin2.setAdapter(dataAdapter);
}

And the spinner will display the values, while having their ids (from the database) too.

In order to retrieve the id of the currently selected item, you do this :

int databaseId = Integer.parseInt ( ( (SpinnerObject) spin2.getSelectedItem () ).getId () );

Please try it and let me know what happens.