I am using Helios on Mac Snow Leopard. I don\'t know why but all of a sudden my arrow keys and delete button start not working only on Eclipse (so Eclipse ignores them) but
I was able to "restore" arrow and backspace keys by "Refreshing" the project.
Using eclipse JUNO on Win XP I also experience this issue. Restarting the workbench using File > Restart does not work, but closing eclipse and starting again with -clean at the command prompt the keys start functioning again, without restart windows.
Had, similar problem with not working “enter” and “delete”, none of above methods helped me – to fix problem I had to switch to default java formatter (one I was using somehow stopped working)
Also check that someone has not installed the vrapper
plugin so that Eclipse accepts vi/vim like commands. If this is the case pressing i
allows you access the editor window. If you are unaware that a work college has installed it (glares at someone) it can be a right $%#&$@! If installed there will be a V icon in the top toolbar. This plugin can be removed by going to the directory where Eclipse is installed in a term window and running
find . -name '\*vrapper\*' -exec rm -rf {} \;
It is that or tax you brain but supposedly increase your productively by learning all the Vim commands. Hope this helps someone...
UPDATE: 7/11/2017 I've not had this problem reoccur in a couple of years now. Either Eclipse fixed the problems or a more recent version of Mac OSX has fixed something. For the record I'm running Eclipse 4.5.2 on OSX 10.11.6.
UPDATE: 4/29/2011 Now it looks like this is not a Workspace or keyboard preferences issue at all. This just happened again but restoring from older Workspaces did not fix the issue. I finally had to reboot my Mac which seemed to resolve things. I'm going to try a restart in the future immediately if I see this again. I've submitted this bug with Eclipse. Please add a "me too" comment to the bug if it has not been fixed and you can reproduce this on your system.
I also have heard that on Macs, you can solve this by getting the unit to sleep either by closing the laptop lid or pulling the Apple menu down to sleep, wait a few seconds, and then starting it again. I've not tried this yet.
BTW, when this happens refreshing and other mechanisms have not worked.
UPDATE: 4/13/2011 Although the below instructions did fix my keyboard issues, I discovered other problems with my configuration and was finally forced to recover my Workspace from backups.
NOTE: This is not recommended but is here for information purposes. Typically these keys are handled by the native widget and are not defined.
So I just had the same problem under Eclipse 3.6.2.r362 on Mac OSX 10.6.7. Delete to the left and arrows not working. They worked in other applications. Option-Arrows worked fine to move a selection around. Arrows worked in the keyboard preferences window. Switching to another application and back didn't work. Restarting eclipse made no difference. Switching keyboard schemes from Emacs -> Default -> Emacs didn't work. Pressing all of the modifier keys did nothing. I tried all of the following and nothing works: Rebuilding the project, refreshing the source, restarting Eclipse.
Finally, I was able to fix this by going to the Preferences -> General -> Keys and resetting each of the bindings for the following keys. The bindings for each of the keys were blank.
Delete Previous
to backspaceLine Up
to up arrowLine Down
to down arrowPrevious Column
to left arrowNext Column
to right arrowThis worked but then I noticed that all of the emacs key bindings were screwed. I thought they worked before so I'm not sure when this happened. I had to restore default key bindings (after writing down the ones that I had customized) and then restore my customized settings.
Makes me wonder what other key bindings have been reset and what did it. Frustrating but at least I can get back to coding.
For me, the root cause was my mouse.
Backspace and navigation keys did not work. I could fix this temporarily by manually setting the key bindings as described on this page.
The root cause and permanent solution was fixing the stuck 3rd mouse button on my Evoluent Vertical Grip mouse. Since I never used that button, I didn't notice that it was permanently engaged, probably from the mouse sliding off the desk on to the ground one too many times. Once I was able to get the button unstuck, the problem was solved immediately.
This was really frustrating. I spent weeks wondering why it was happening and sporadically searching the web for answers. Of course I had a temporary solution, but the fact that it kept happening was annoying. I tried reinstalling Eclipse from scratch, trying different versions and switching workspaces, but nothing worked. I'm surprised it ended up being a stuck mouse button after all that.