Qt vs Java / Swing
When comparing Qt vs Java / Swing, the Slant community recommends Qt for most people. In the question“What are the best cross-platform GUI toolkits?” Qt is ranked 2nd while Java / Swing is ranked 16th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Open-source
Pro Global community
The community behind Qt is both massive and approachable. Digia (also owners) are joined by the likes of Intel, KDAB, ICS, Canonical and numerous others in sponsoring development, while communities such as KDE also contribute significantly. Forums are active, mailing lists are open, irc channels chatting, git repositories well managed. Answers to questions are usually minutes away.
Pro Good documentation
Professional, thorough documentation with examples, available either in a web browser or in the stand-alone desktop client called assistant.
Pro Part of Java
Swing is part of the Java API.
Pro Very good and powerful API
E.g. separate models.
Pro Powerful controls
E.g. JTable which works fine on every platform with very large row counts, e.g. 100.000+.
Pro Several look and feels available
Pro Easy to use
Drag and drop utility.
Cons
Con Only for JRE-based languages
Con Bugfixes rely on Oracle
Con No real native look
Though the importance of the native look seems to have dropped the last years by the raise of in-browser-applications.
However, you can achieve native look and feel using UIManager.systemLookAndFeelClassName.
Con Severely deprecated
The system is ancient and Oracle has dropped support for it in favor of JavaFX