List Model Controls - The Definitive Guide to Java Swing - page 482

Four essential elements define the JComboBox component and its implementation:

A data model for holding the JComboBox data, as defined by the ListModel interface

•

• A cell renderer for drawing the elements of the JComboBox , as described by the

ListCellRenderer interface

• An editor for entering choices not part of the predefined data model, as defined by the

ComboBoxEditor interface

A keystroke manager for handling keyboard input to select elements of the JComboBox , as
described by the KeySelectionManager interface

•

Many of the JComboBox capabilities are shared with the JList component. This isn't accidental;
the two components are fairly similar. Let's now look at the JComboBox in more detail.

Creating JComboBox Components
Like the JList component, the JComboBox component has four constructors, allowing you to
create one based on your initial data structure. Unlike the JList component, the default model
used by the array and Vector constructor permits adding and removing data elements.

public JComboBox()
JComboBox comboBox = new JComboBox();

public JComboBox(Object listData[])
String labels[] = { "Chardonnay", "Sauvignon", "Riesling", "Cabernet", "Zinfandel",
"Merlot", "Pinot Noir", "Sauvignon Blanc", "Syrah", "Gewürztraminer"};
JComboBox comboBox = new JComboBox(labels);

public JComboBox(Vector listData)
Vector vector = aBufferedImage.getSources();
JComboBox comboBox = new JComboBox(vector);

public JComboBox(ComboBoxModel model)
ResultSet results = aJDBCStatement.executeQuery("SELECT columnName FROM tableName");
DefaultComboBoxModel model = new DefaultComboBoxModel();
while (result.next())
model.addElement(results.getString(1));
JComboBox comboBox = new JComboBox(model);

JComboBox Properties
After you create a JComboBox component, you can modify each of its many properties. Table 13-10
shows the 22 properties of JComboBox .