In Ubuntu, if you are finding the alternate of Microsoft Visual Studio then DIA is the best choice. Dia helps you to draw your UML diagrams like class diagrams, object diagrams, use-case diagrams, sequence diagrams, activity diagrams, flow charts, and many other types of diagrams displayed in the last screenshot. Due to drag and drop facility, you can easily draw any diagram in no time.
You can download it from UCS [Ubuntu Software Center]. And here is the some screenshots of the DIA software.
You can download it from UCS [Ubuntu Software Center]. And here is the some screenshots of the DIA software.