I have the following JLabel code:
JLabel someJLabel = new JLabel("<html>first line<br>second line</html>");
someJLabel.setFont(new Font("Arial", Font.PLAIN, 16));
What I'd like to do is be able to control the line height/spacing between the two lines.
PS: I've also looked at using paragraphs instead of breaklines, but it's the same thing. And I don't know if you can do that within an html tag without using css (you can't use css within html code in a JLabel in Java Swing).
This should work, but it's not. color: green works though.
content.add(new JLabel("<html><p style=\"line-height: 150%;\">hi<br>world</p></html>"));
I guess line-height doesn't work. That's how you'd do it if you were to use CSS, so maybe you can't do it that way. Here's a nice tool I found which you can use to test if your HTML will work quickly.
Check out the setStyleSheet(...) method of the HTMLEditorKit. I've never used it before but I believe it provides some basic support.
Otherwise you can use a JTextPane to control the line spacing. I think you would use:
StyleConstants.setLineSpacing(...);
You can then change the foreground/background etc to make the text pane look like a label.
Hmm .. CSS in JLabel seems to work for me, if one sticks to supported properties. Try padding (or margin) and font-size:
someJLabel = new JLabel("<html><body><p style=\"padding:10; font-size:30\">First line</p><p style=\"padding:10; font-size:20\">Second line</p></body></html>");
Because of Java supports <p> tag and CSS margin attribute you can use next solution:
new JLabel("<html>first line<p style='margin-top:-5'>second line");
P.S. Now it is not required to close html tags.
You could try using two labels, and setting the distance between the two, as well as the whitespace, using a LayoutManager. I like GridBoxLayout, myself.
Edit: GridBagLayout. Whoops!
Does setting empty border helps, like
label.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
method syntax BorderFactory.createEmptyBorder(int top, int left, int bottom, int right)
来源：https://stackoverflow.com/questions/3113386/how-to-set-line-spacing-height-in-a-jlabel-in-java-swing