JComboBox.getItemCount() has the following syntax.
public int getItemCount()
In the following code shows how to use JComboBox.getItemCount() method.
// w w w. j a v a 2s . c om import java.awt.Dimension; import java.awt.event.ActionEvent; import java.util.Vector; import javax.swing.AbstractAction; import javax.swing.ComboBoxEditor; import javax.swing.JComboBox; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.plaf.ComboBoxUI; public class Main extends JFrame { JComboBox jcb; Main(String title) { super(title); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel jp = new JPanel(); Vector v = new Vector(); v.add("A"); v.add("B"); v.add("C"); jcb = new JComboBox(v); jcb.setEditable(true); jcb.getActionMap().put("selectNext", new DownAction()); jp.setPreferredSize(new Dimension(200, 35)); jp.add(jcb); getContentPane().add(jp); pack(); setVisible(true); } public static void main(String[] args) { new Main("Binding Demo3"); } } class DownAction extends AbstractAction { public void actionPerformed(ActionEvent e) { JComboBox jcb = (JComboBox) e.getSource(); System.out.println("down action"); ComboBoxUI ui = jcb.getUI(); if (ui.isPopupVisible(jcb)) { int i = jcb.getSelectedIndex(); if (i < jcb.getModel().getSize() - 1) { jcb.setSelectedIndex(i + 1); jcb.repaint(); } } else { int nItems = jcb.getItemCount(); ComboBoxEditor cbe = jcb.getEditor(); String st; // Search text st = ((String) cbe.getItem()).toUpperCase(); for (int i = 0; i < nItems; i++) { String item = ((String) jcb.getItemAt(i)).toUpperCase(); if (item.startsWith(st)) { jcb.setSelectedIndex(i); break; } } ui.setPopupVisible(jcb, true); } } }