I checked the preferences settings in my Eclipse, it\'s all set to default with sysout option on, but when I typed sysout in eclipse, it won\'t automatically go into S
After trying all the answers above with no success I found another reason why Ctrl+Space could be prevented from working.
In my instance Ctrl+Space worked for some projects in the workspace but not others. I discovered that the project that it did not work for did not have the jdk in the build path, instead it had the jre for the application server (weblogic 12). The application ran fine on the server but Ctrl+Space to open the template proposals didn't work and other things like syntax highlighting were not quite right.
I hope this helps anyone who comes to this questions 3 years after it was asked (Like I did).