@startuml Figure_1.5
' TreeMap_CollaborationDiagram

actor Actor
rectangle "<u>:TreeMap</u>" as TreeMap
rectangle "<u>topNode</u>\n<u>:TreeMapNode</u>" as topNode

Actor   -right-> TreeMap : "1: add(key, value)\n<size:24><&arrow-right></size>"
TreeMap -down->  topNode : "<size:24><&arrow-bottom></size>[topNode != null]\n          1.1: add(key, vaule)"

'Others icons
'<&arrow-left>
'<&arrow-right>
'<&arrow-top>
'<&arrow-bottom>
'<&loop-circular>
@enduml