如何将另一个LayoutManager应用于JComboBox？ （多列JComboBox尝试）

I'm trying to make a multi-column JComboBox. I've looked around quite a bit and it seems to be a very tricky thing to do. Unless many people, I'm not interested in having a table (where you select a row): I need to eliminate the scroll bar in the JComboBox and, in order to achieve this, I want to lay its items in a multi-column list instead of having them in only one column.I'm trying to make a multi-column JComboBox. I'