What is the best and powerful tool for building swing interface? What tool do you use for swing? Why?
Netbeans comes with a nice GUI builder, look here: http://java.sun.com/developer/technicalArticles/tools/nb_guibuilder/
NetBeans Matisse (comes bundled with NetBeans) is good and powerful.
This eclipse plugin seems fresh as well, but I haven't tried it.
Eclipse is my IDE of choice. You can download Eclipse Visual Editor Project(VEP) from here. take a look at this tutorial.
The Eclipse Visual Editor project is a vendor-neutral, open development platform supplying frameworks for creating GUI builders, and exemplary, extensible tool implementations for Swing/JFC and SWT/RCP.
if you want some compression between Eclipse's VEP and NetBeans' Matisse, take a look at this and this.
The Netbeans builder can be quite nice, but it does build a lot of code for some simple tasks. So over time I have gone back to coding by hand, it can save you a lot of time in the long run!
I prefer coding by hand with GridBagLayout, but if I had to use a GUI-Builder I would use NetBeans.
I have written a Qt-style wrapper around GridBagLayout and I handcode my GUIs using it.
Visual GUI builders certainly provide more flexibility but that comes at the cost of reduced readability of the code. However I do use NetBeans Matisse when I have some quick and dirty job at hand. ;)
Anyway...
If you are interested in handcoding GUIs at all, then you might also like to have a look at MigLayout. I have never tried it though.
Abeille Forms is pretty good. It's based on JGoodies FormLayout. With Abeille you can layout your components visuals and access and/or replace the component with a richer component at runtime.
JFormDesigner is a nice visual designer. It supports lots of open source and built-in swing Layout, it has a plugin support for Eclipse,IntelliJ and also can be used external designer.I have used it as an IntelliJ plugin in a multi-year big swing project with no problem.