Add listener to ArrayList

Question

I have an ArrayList which I add some Objects to it dynamically, and I have a JButton. The ArrayList is empty when running my program and the JButton is set to setEnabled(fal

Answer 1

ObservableList ol = FXCollections.ObservableArrayList(new ArrayList());
ListProperty lp = new SimplePropertyList(ol);

lp.addListener(new ChangeListener() {
    @Override public void changed(ObservableValue o, Object oldVal, Object newVal) {
        if (ol.size() > 1 && !JButton.isEnabled()) {
            JButton.setEnable(true);
        } else if (ol.size < 2 && JButton.isEnabled()) {
            JButton.setEnable(false);
        }
    }
});