How good of a job did this tutorial do in making you prepared to write your own programs?
Hmm to be honest, SoloLearn has the basics down and you can definitely hit the ground running writing programs. However, this app has its limitations, while it presents the concepts, it does not present the real world usage of those concepts very well and its missing huge chunks of information on say making graphics in Java and how to write a complete program from beginning to end. I guess you'd need to do your own research on those. But I do have to say, Sololearn is a great reviewing tool, for say if you're new in CompSci and you want to test the concepts you've learned using a different source and be excited about learning!