If the combobox is editable, the new value can be any value : JComboBox « Swing « Java Tutorial

1. Java Tutorial
2. Swing
3. JComboBox

import javax.swing.JComboBox;

public class Main {
  public static void main(String[] argv) throws Exception {
    // Create a read-only combobox
    String[] items = { "item1", "item2" };
    JComboBox cb = new JComboBox(items);

    cb.setEditable(true);
    cb.setSelectedItem("item3");
    Object obj = cb.getSelectedItem(); 

  }
}

14.12.JComboBox
	14.12.1.	Creating JComboBox Components
	14.12.2.	Add Items to JComboBox
	14.12.3.	Get selected Item from JComboBox
	14.12.4.	Getting and Setting the Selected Item in a JComboBox Component
	14.12.5.	Editable JComboBox
	14.12.6.	If the combobox is editable, the new value can be any value
	14.12.7.	Listen to JComboBox with ItemListener
	14.12.8.	Sharing the Data Model between two JComboBoxes
	14.12.9.	Sharing the Data Model for a JComboBox and JList
	14.12.10.	Editing JComboBox Elements
	14.12.11.	Listening to Keyboard Events with a KeySelectionManager
	14.12.12.	A Color Combo Box Editor
	14.12.13.	Setting ComboBox Editor and ComboBox Renderer
	14.12.14.	Combobox cell renderer
	14.12.15.	Custom JComboBox Pop-up Button
	14.12.16.	JComboBox Using the Custom Model
	14.12.17.	Get Model from JComboBox and set it to JList
	14.12.18.	Adding and Removing an Item in a JComboBox Component
	14.12.19.	Add an item to the end of the list
	14.12.20.	Add an item after the first item
	14.12.21.	Getting the Items in a JComboBox Component
	14.12.22.	Remove first item
	14.12.23.	Remove the last item
	14.12.24.	Remove all items
	14.12.25.	Determining When the Menu of a JComboBox Component Is Displayed
	14.12.26.	Listening for Action Events from a JComboBox Component
	14.12.27.	Listening for Changes to the Selected Item in a JComboBox Component
	14.12.28.	Setting the Number of Visible Items in the Menu of a JComboBox Component
	14.12.29.	Displaying the Menu in a JComboBox Component Using a Keystroke If the Selected Item Is Not Unique
	14.12.30.	Determining If the Menu of a JComboBox Component Is Visible
	14.12.31.	Displaying the Menu in a JComboBox Component Using a Keystroke
	14.12.32.	Selecting an Item in a JComboBox Component with Multiple Keystrokes
	14.12.33.	Customizing a JComboBox Look and Feel