JLabel label = new JLabel(\"Hello world\");
shows nothing.
If I get rid of the tags, it
If you want to mix fonts or colors within the text, or if you want formatting such as multiple lines, you can use HTML. HTML formatting can be used in all Swing buttons, menu items, labels, tool tips, and tabbed panes, as well as in components such as trees and tables that use labels to render text.
Refer this example HtmlDemo.java
In your example
JLabel label = new JLabel("Hello world");
you are not applying any formating like bold or italic etc..
also is not required.
Hope it helps.