java第三次实验代码.doc

Java第三次试验代码： 【代码1】：??setModal(true);【代码2】：??setVisible(false);????????【代码3】：??setVisible(false);????????????????【代码4】：??new?FontDialog(this);【代码5】：??setVisible(true);【代码6】：??dialog.setTitle(字体对话框);?李芳??20:05:09import?java.awt.*;import?java.applet.*;import?java.awt.event.*;?class?SignalCanvas?extends?Canvas?{??int?red,green,yellow,x,y,r;???SignalCanvas()???{??setBackground(Color.white);???}???public?void?setRed(int?r)???{???red=r;???}???public?void?setGreen(int?g)???{???green=g;???}???public?void?setYellow(int?y)???{???yellow=y;???}???public?void?setPosition(int?x,int?y)???{??this.x=x;??????this.y=y;???}???public?void?setRadius(int?r)???{??this.r=r;???}???public?void?paint(Graphics?g)???{??if(red==1)???????{??g.setColor(Color.red);???????}??????else?if(green==1)?????????????{??g.setColor(Color.green);??????????}?????else?if(yellow==1)???????{??g.setColor(Color.yellow);??????????}??????g.fillOval(x,y,2*r,2*r);???}}?class?SignalFrame?extends?Frame?implements?ItemListener??{??Choice?choice;????SignalCanvas?signal=null;????String?itemRed=红灯,itemYellow=黄灯,itemGreen=绿灯;????public?SignalFrame()????{??choice=new?Choice();?????//创建choice????choice.add(itemRed);???????????????//创建choice添加itemRed????choice.add(itemYellow);???????????????//创建choice添加itemYellow?????choice.add(itemGreen);????????????????//创建choice添加itemGreen??????choice.addItemListener(this);??//将当前窗口注册为choice的ItemEvent事件监视器??????String?item=?choice.getSelectedItem();??//?choice返回被选中的条目???????add(choice,BorderLayout.NORTH);???????try{??Class?cs=Class.forName(SignalCanvas);?????????????signal=(SignalCanvas)cs.newInstance();?????????????add(signal,BorderLayout.CENTER);???????????}????????catch(Exception?e)???????????{?add(new?Label(您还没有编写SignalCanvas类),BorderLayout.CENTER);???????????}????????setBounds(100,100,360,300);???????setVisible(true);???????validate();???????addWindowListener(new?WindowAdapter()?????????????????????????{??public?void?win