import java.applet.*;
import java.awt.*;
public class checkboxdemo extends Applet
{
Checkbox checkbox1,checkbox2,checkbox3;
boolean lbool=false,bbool=false,ibool=false;
Button button1;
String text="";

public void init()
{
resize(320,200);
checkbox1=new Checkbox("LARGE");
checkbox2=new Checkbox("BOLD");
checkbox3=new Checkbox("ITALIC");

button1=new Button("clear");

add(checkbox1);
add(checkbox2);
add(checkbox3);
add(button1);
}
public boolean action(Event e,Object o)
{
if(e.target.equals(checkbox1))
{
lbool=!lbool;
}
if(e.target.equals(checkbox2))
{
bbool=!bbool;
}
if(e.target.equals(checkbox3))
{
ibool=!ibool;
}
if(e.target.equals(button1))
{
text="";
}
repaint(); //什么意思，起到什么作用！
return true; //返回真在本程序是什么意思?改成False也无碍！
}
public boolean keyDown(Event e,int k)
{
text=text+(char)k;
repaint();
return true;
}

public void paint(Graphics g)
{
String fontname="Roman";
int type=Font.PLAIN;
int size=24; //把什么设置成24？
Font font;
if(bbool)
{
type=type|Font.BOLD;
}
if(ibool)
{
type=type|Font.ITALIC;
}
if(lbool)
{
size=48;
}
font=new Font(fontname,type,size);
g.setFont(font);
g.drawString(text,20,100);
}
}

问题：
以上三句带颜色的句子都是什么意思？请高手赐教？多谢！！

可我把int size改成48后，运行后也没有变化呀？

import java.applet.*;
import javax.swing.JCheckBox;
import javax.swing.JButton;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


public class checkboxdemo extends Applet
{
  JCheckBox checkbox1,checkbox2,checkbox3;
  JButton button1;
  int type = Font.PLAIN;
  int size=24;

  String text=\"\";
    
  public void init()
  {
    resize(320,200);
    checkbox1=new JCheckBox(\"LARGE\", false);
    checkbox2=new JCheckBox(\"BOLD\", false);
    checkbox3=new JCheckBox(\"ITALIC\", false);

    //Register a listener for the check boxes.
    checkbox1.addActionListener(new checkboxdemo.FontTypeChoice());
    checkbox2.addActionListener(new checkboxdemo.FontTypeChoice());
    checkbox3.addActionListener(new checkboxdemo.FontTypeChoice());

    
    button1=new JButton(\"clear\");
    //Register a listener for button1.
    button1.addActionListener(new MyButtonActionListener());
    
    add(checkbox1);
    add(checkbox2);
    add(checkbox3);
    add(button1);
  }
  
  public void paint(Graphics g)
  {
    super.paint(g);
    String fontname=\"Roman\";
    int type=Font.PLAIN;
                                              
    Font font = new Font(fontname,type,size);
    g.setFont(font);
    g.drawString(text,20,100);
  }
  class FontTypeChoice implements ActionListener
  {
    /** Listens to the check boxes. */
    public void actionPerformed(ActionEvent e)
    {
      String sizeStr = \"Normal\";
      String typeStr = \"Plain\";     
      
      if((checkbox2.isSelected() == false) && (checkbox3.isSelected() == false))
      {
        type = Font.PLAIN;
        typeStr = \"PLAIN\";
      }
      else if((checkbox3.isSelected()) && (checkbox2.isSelected() == false))
      {  
        type = Font.ITALIC;
        typeStr = \"ITALIC\"; 
      }
      else if(checkbox2.isSelected() && (checkbox3.isSelected() == false))
      {  
        type = Font.BOLD;
        typeStr = \"BOLD\"; 
      }      
      else if(checkbox2.isSelected() && checkbox3.isSelected())
      {  
        type = Font.BOLD | Font.ITALIC;
        typeStr = \"BOLD | ITALIC\"; 
      }
      
      
      if(checkbox1.isSelected())
      {
        size = 48;
        sizeStr = \"Large\";   
      }
      else if(checkbox1.isSelected() == false)
      {  
        size = 24;
        sizeStr = \"Normal\"; 
      }
      text = sizeStr + \" \" + typeStr;

      repaint();
    }
  }
  class MyButtonActionListener implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      Object o = e.getSource();
      if(o.equals(button1))
      {
        text=\"\";
        checkbox1.setSelected(false);
        checkbox2.setSelected(false);
        checkbox3.setSelected(false);
        repaint();
      }
    }
  }
}

我天天上来看，怎么也没人给我回贴呀，是不是我问的有什么问题呀？NULL：你这是回答我问题呢还是问问题呢？我运行你的程序怎么老提示出问题呀？

编译到是成功了。就是网页上提示JAVA运行出错？