I use eclipse luna to program in java, I have it installed, and I can open it well, but when I'm in a JFrame class and edit the code, every time I edit it, the following appears:
I enter the code, but it has no errors. I close eclipse, and when I open it again it works perfect, until I edit the code again, and I have to close it again. It is difficult for me to work this way and I do not know what could be happening, install it from the page that our teacher sent us and in the way he told us, install java beforehand, etc.