Java programming course: 14.8 JComboBox

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JComboBox

The JComboBox class allows the user to select an item using a drop-down list:

JComboBox colourCombo = new JComboBox();
colourCombo.addItem("Red");
colourCombo.addItem("Green");
colourCombo.addItem("Blue");
panel.add(colourCombo);
 

It looks like this:

If you click on the small down-pointing arrow to the right of the option, then the other options will appear:

You can select the item required either with the mouse or the keyboard. If there are lots of items, then a vertical scrollbar will automatically appear. To obtain which item was selected you can either use getSelectedItem() which returns an Object, or getSelectedIndex() which returns an int, being the position in the list of the selected item (where zero is the first item, etc.):

String selectedColour = (String) colourCombo.getSelectedItem();
int selectedIndex = colourCombo.getSelectedIndex();
 

• Note that you need to cast the Object returned from getSelectedItem() back into a String, since it was String objects which you added to the component.

Next lesson: 14.9 JSlider