Cooperative multitasking

Got a telephonic round first which comprised of java based GUI swing questions like repaint and revalidate method, creating a jtreetable and checkbox in a column, rendering, how will you manage if you want to populate bulk of data in your GUI and your GUI hangs, multithreading in the GUI, socket programming basics, file input output basics. Then appeared for the technical face to face discussion - two techies were there ready with the whiteboarding stuff and all, they asked about string class, string immutability and string builder and buffer mutability, overloading and overriding string methods some how, then to create a custom split function which takes a char instead of string to split - focus was the approach mainly and usage of collections and ds, then a high level design for a test framework to be created and then the design patterns question - focus was factory object pattern, then in the managerial round - he was very cool and just briefed me about the work profile and culture, the hr was also very cool and well behaved with some basic hr questions.