如何在JPopupMenu中选择第一项？

JMenuItem firstItem = (JMenuItem) popupMenu.getComponent(0);

firstItem.doClick();

JPopupMenu popupMenu = new JPopupMenu();
JMenuItem menuItem1 = new JMenuItem("菜单项1");
JMenuItem menuItem2 = new JMenuItem("菜单项2");
JMenuItem menuItem3 = new JMenuItem("菜单项3");

popupMenu.add(menuItem1);
popupMenu.add(menuItem2);
popupMenu.add(menuItem3);

// 显示弹出菜单
popupMenu.show(button, 0, button.getHeight());

// 获取第一项菜单项
JMenuItem firstItem = (JMenuItem) popupMenu.getComponent(0);

// 模拟点击第一项菜单项
firstItem.doClick();