List Component

[Prosis]

I need to know some things about a List Component:

1-How do make it so that when a user clicks on many list items they all stay selected. What I mean is that you click on the first item and then on the second then on the third, then the three first items will be selected. Then when you click on the second, the first and third will be selected.

2-Is there a "isSelected" method to use so that on the press of a button I can show data concerning only the items selected?

Thank You!