Adding text in to text area of jframe at new line with different background colour

import java.io.*;
import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.text.*;

public class TextAreaExample {
    public static void main(String[] args)throws Exception{
        JFrame f = new JFrame("First JTextPane Example");
        f.getContentPane().setLayout(new BorderLayout());

        JTextPane text = new JTextPane();
        Random r = new Random();

        BufferedReader br=new BufferedReader(new FileReader("data.txt"));
        String str=" ";

        StyledDocument doc = text.getStyledDocument();

        Style style = text.addStyle(" ", null);
        while((str=br.readLine())!=null){
            Color randomColor = new Color(r.nextInt(256),r.nextInt(256),r.nextInt(256));
            StyleConstants.setForeground(style, randomColor);
            try { doc.insertString(doc.getLength(), str,style);
            doc.insertString(doc.getLength(), "\n",style);
            }
            catch (Exception e){}
        }
        f.getContentPane().add(text, BorderLayout.CENTER);
        f.setSize(350, 250);
        f.show();
    }
    }