In Eclipse, how can I make a toolbar button, or menu command, that modifies my current selection?

I want to make a toolbar button in eclipse that when pressed, removes all newlines from my selec开发者_如何转开发tion.

How can I do this?

You'll need to create a plugin for Eclipse. Take a look at PDE: http://www.eclipse.org/pde/

But maybe this plugin does what you need: http://andrei.gmxhome.de/anyedit/

As @Paulo suggested, you'll need an Eclipse plugin. More specifically, it sounds like you'll need a java editor extension. The Eclipse plugin development version that you can download and setup has some fairly easy wizards such as editor extensions and toolbar contributions - from there it is a matter of figuring out how to tie it together.