import javax.swing.JTextPane;
import javax.swing.text.Style;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyledDocument;
public class Main {
public static void main(String[] argv) throws Exception {
JTextPane textPane = new JTextPane();
StyledDocument doc = (StyledDocument) textPane.getDocument();
Style style = doc.addStyle("StyleName", null);
StyleConstants.setFontFamily(style, "SansSerif");
// Append to document
doc.insertString(doc.getLength(), "Some Text", style);
}
}