Ctrl + F11 is the \"Run\" keyboard shortcut in Eclipse.
But for me, that only works if a Main class is active in the editor. For any of the other 1
Check the preferences, Launching section - you may want to switch from "launch selection" to "launch previously launched application".
You can configure Eclipse to always use the previously launched application: Window → Preferences → Run/Debug → Launching → Always launch the previously launched application. This almost always does what you want.