GUI program, problem with tabbedpanes

Answer 1

To answer your specific question about using three panels instead of 1, I would suggest two. There's rarely a need to create a panel just to create a single widget. So, one widget for the name and sentence, one for the crime.

As for the question about "is there a better way to design this"?... It sounds like you are learning, so I suggest you don't focus too much on the perfect way to do it. Stick with your original design then after the task is done ask yourself what worked* and what didn't. With that information you'll be able to decide for yourself whether what you did was the right design.

There usually isn't a "best" when designing GUI code -- there are many ways to solve the problem. What you've described sounds like a perfectly good way to attack the problem

(*) "worked" in this context means, was it easy to code? Did it allow you to achieve the layout you desired? Does it make the code maintainable over time if, for example, a requirement comes down to reorganize the GUI?.

Answer 2

Bryan gave good advices, I will just add that ergonomics isn't an exact science, although experience helps there.
Tabs are nice, eg. to separate settings, or group in a same panel (toolbox for example) different sets of tools (layers, colors, brushes...).
But they might not be adapted to all workflows. But we are lacking information about the role of the Display tab. Is it supposed to list all crimes in a table? Can't the table, if any, be below the controls?

As hinted by Bryan, it is better to design the GUI, then to test it, like would do a real user. Do you find the workflow easy to understand? (make somebody else to test it!) Does the usage feels natural? Is it fast to use?
Then you can adjust the design in light of these observations.

Answer 3

You were right to create InputPanel and DisplayPanel as seperate classes.

As for further splitting those panels? Yes you should further split them up, but not into separate classes. You should add jPanels inside of your InputPanel, and DisplayPanel, and group the controls within those internal jPanels.

Please let me know if you would like me to clarify what I mean.