Show dotted lines in a JTreeTag(s): Swing
In your code
Or from the command line
... tree.putClientProperty("JTree.lineStyle", "Angled"); ...
Other possible values :
java -DJTree.lineStyle=Angled MyApp
None No lines are drawn anywhere on the tree. Angled Vertical lines between nodes at the same level, horizontal line to child node. Horizontal A single horizontal line between nodes immediately attached to the root node. This is the default setting.