网页没有显示在我的简单网络浏览器中（用Java编写）

我只是做了一个简单的网络浏览器。但是浏览器实际上无法显示任何内容。输入URL并按Enter后，什么也没有发生。浏览窗口保持灰色。哪里错了？

package readfile;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class ReadFile extends JFrame{
    private JTextField addressbar;
    private JEditorPane display;

    public ReadFile(){
        super("My Browser");
      addressbar=new JTextField("Enter a hoss");
        addressbar.addActionListener(

        new ActionListener() {

            //@Override
            public void actionPerformed(ActionEvent event) {
                //throw new UnsupportedOperationException("Not supported yet.");//To change body of generated methods, choose Tools | Templates.
                loadCrap(event.getActionCommand());



            }  

        }


        );
        add(addressbar,BorderLayout.NORTH);
        display=new JEditorPane();

        display.setEditable(false);
        display.addHyperlinkListener(
        new HyperlinkListener() {

            //@Override
            public void hyperlinkUpdate(HyperlinkEvent event) {
                //throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

            //event.getEventType(event.);

            if(event.getEventType()==HyperlinkEvent.EventType.ACTIVATED){

                loadCrap(event.getURL().toString());



            }

            }
        }

        );

    add(new JScrollPane(),BorderLayout.CENTER);


    //add(new JScrollPane(),BorderLayout.CENTER);

    setSize(500,300);

        setVisible(true);

    }



    private void loadCrap(String userText){


        try {
            display.setPage(userText);
            addressbar.setText(userText);

        } catch (Exception e) {
            System.out.println("Crap");
        }

    }

}

面类：

    package readfile;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

import javax.swing.JFrame;

public class ReadFileMain {

    public static void main(String[] args) {

    ReadFile rf=new ReadFile();
    rf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);


    }

}