I m used sololearn from last 1 year . I m learn java, sql, html, css, JavaScript , c+ from here .
Its user interface are too good. Itz give coding platform also .if u don’t have Laptop and computer but u want to work on java then in sololearn u can work on u r phone also.
When you complete 1 chater quiz start nd then you go to next chapter .
Very good learning app .