import java.awt.event.KeyEvent;
import javax.swing.JButton;
import javax.swing.JTabbedPane;
public class Main {
public static void main(String[] argv) throws Exception {
JTabbedPane pane = new JTabbedPane();
pane.addTab("Tab Label", new JButton("button"));
int index = pane.getTabCount() - 1;
int keycode = KeyEvent.VK_L;
pane.setMnemonicAt(index, keycode);
}
}