JavaFX - object data to TableView

Question

Have data from db in ResultSet - working good - line System.out.println(alarm.toString()); prints data OK.

Trying to put the data into TableView - something wrong - line System.out.println(data.toString()); - prints last line X NUMBER OF RECORDS, the same in TableView - only last line duplicated a lot.

public void setAlarmsTableView(ResultSet rs) throws SQLException {
    private ObservableList<AlarmType> data = FXCollections.observableArrayList();
    columnDeviceIndex.setCellValueFactory(new PropertyValueFactory<>("deviceIndex"));
    /* ... */
    columnAlarmTime.setCellValueFactory(new PropertyValueFactory<>("alarmTime"));

    AlarmType alarm = new AlarmType();
    while (rs.next()) {
        alarm.setDeviceIndex(rs.getInt(1));
        /* ... */
        alarm.setAlarmTime(rs.getTimestamp(8));
        alarmsTableView.getItems().add(alarm);
        data.add(alarm);
        System.out.println(alarm.toString());
    }
    alarmsTableView.setItems(data);

    System.out.println(data.toString());
}

fabian · Accepted Answer · 2018-02-03 14:23:07Z

1

You only ever create & modify a single AlarmType instance. You need to create one instance per ResultSet row however. Also I'm not sure adding the instance to both the items list of the TableView and the data list is neccessary.

// AlarmType alarm = new AlarmType();
while (rs.next()) {
    AlarmType alarm = new AlarmType(); // create new instance here
    alarm.setDeviceIndex(rs.getInt(1));
    /* ... */
    alarm.setAlarmTime(rs.getTimestamp(8));
    // alarmsTableView.getItems().add(alarm); // this shouldn't be necessary
    data.add(alarm);
    System.out.println(alarm.toString());
}
alarmsTableView.setItems(data);

edited Feb 3, 2018 at 14:23

answered Feb 3, 2018 at 13:33

fabian

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1 Comment

Yahya Over a year ago

That's absolutely right, all AlarmType(s) in the Table point to the same object created at the beginning. Nice observation.

ehr · Accepted Answer · 2018-02-03 14:13:48Z

0

Ok, I finally did something like that.

    AlarmType alarm = new AlarmType();
    while (rs.next()) {
        alarm.setDeviceIndex(rs.getInt(1));
        /* ... */
        alarm.setAlarmTime(rs.getTimestamp(8));
        data.add(new AlarmType(alarm));
    }
    alarmsTableView.setItems(data);

The table is full of data, and I'm satisfied learned my fault. @fabian @Yahya Thanks a lot for help!

answered Feb 3, 2018 at 14:13

ehr

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2 Comments

fabian Over a year ago

Why create a additional AlarmType to hold the data when you're creating a new one from the data anyway? This way your code uses 4 assignments instead of 2: 2 in the setters and 2 in the copy constructor. If you simply create & fill a new instance inside the loop body you only need the 2 assignments for the setters.

ehr Over a year ago

U mean while loop included only data.add(new AlarmType(rs.getInt(1), /*...*/ ,rs.getTimestamp(8)));? Yup! U re deadly right! I should have been refacroted code before creating the question

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