Today, looking at the code I wrote, I originally defined the variable name as contentPanel. I mistakenly thought it was wrong and changed it to ContentPanel. When I saw the setContentPane method below, I found that I had not written it wrong, but I was wrong …
So, what is the difference between panel and Panel?
Panel is a panel, which is only a basic component rarely used directly, either inherited and rewritten, or used to organize other components.
Pane is a fully functional and independent sub-pane.
Look at the naming of Swing inside. JPanel is a basic component. However, those who have full functions/perform their duties are called Pane, such as JTabbedPane,JSplitPane.