How to remove the active title bar of a frame?

I have a JFrame which displays a title bar. Active title bar as it's called in Windo开发者_如何学运维ws desktop properties. How to remove this bar?

You can use setUndecorated(boolean undecorated) method in JFrame.

Note: This method can only be called while the frame is not displayable.

frames have titlebars
windows do not
check out http://academicjava.com/Java_help/Tutorial_Examples_Swing_5.html for examples