如果父进行大小调整或JComponent的内容发生变化，如何使JComponent始终填充父事件？

I have a JCombobox and I'm adding some items at runtime. Some of them are very long and my Jcombobox is growing very long too. It's in a JPanel container with BoxLayout (PAGE_AXIS). I have no idea how to prevent growing...I have a JCombobox and I'm adding some items at