J2ME中ITEM类用法实例解析(1)(2)

4、代码（NETBEANS生成的大部分框架，笔者修改了其中几行，增加了ITEM类StateChanged方法）

packagehello;  
importjavax.microedition.midlet.*;  
importjavax.microedition.lcdui.*;  
 
publicclassHelloMIDletextendsMIDletimplementsCommandListener,
ITEM类StateListener{  
privatebooleanmidletPaused=false;  
//  
privateCommandexitCommand;  
privateFormform;  
privateChoiceGroupweather_CG;  
//  
 
publicHelloMIDlet(){  
}  
//  
//  
//  
 
privatevoidinitialize(){  
//writepre-initializeusercodehere  
 
//writepost-initializeusercodehere  
}  
//  
//  
 
publicvoidstartMIDlet(){  
//writepre-actionusercodehere  
switchDisplayable(null,getForm());  
//writepost-actionusercodehere  
}  
//  
//  
publicvoidresumeMIDlet(){  
//writepre-actionusercodehere  
 
//writepost-actionusercodehere  
}  
//  
//  
 
publicvoidswitchDisplayable(Alertalert,
DisplayablenextDisplayable){  
//writepre-switchusercodehere  
Displaydisplay=getDisplay();  
if(alert==null){  
display.setCurrent(nextDisplayable);  
}else{  
display.setCurrent(alert,nextDisplayable);  
}  
//writepost-switchusercodehere  
}  
//  
//  
 
publicvoidcommandAction(Commandcommand,
Displayabledisplayable){  
//writepre-actionusercodehere  
if(displayable==form){  
if(command==exitCommand){  
//writepre-actionusercodehere  
exitMIDlet();  
//writepost-actionusercodehere  
}  
}  
//writepost-actionusercodehere  
}  
//  
//重写ITEM类StateChanged方法  
publicvoidITEM类StateChanged(ITEM类ITEM类){  
//writepre-actionusercodehere  
if(ITEM类==weather_CG){  
form.setTitle("你选择了"+weather_CG.getString
(weather_CG.getSelectedIndex())+"天");  
//writepost-actionusercodehere  
}  
//writepost-actionusercodehere  
}  
//  
 
//  
 
publicCommandgetExitCommand(){  
if(exitCommand==null){  
//writepre-initusercodehere  
exitCommand=newCommand("u9000u51FA",Command.EXIT,0);  
//writepost-initusercodehere  
}  
returnexitCommand;  
}  
//  
//  
publicFormgetForm(){  
if(form==null){  
//writepre-initusercodehere  
form=newForm("Welcome",newITEM类[]{getWeather_CG()});  
form.addCommand(getExitCommand());  
form.setCommandListener(this);  
//增加初始天气选择情况显示  
form.setTitle("你选择了晴天");  
//增加ITEM类的监听器  
form.setITEM类StateListener(this);
//writepost-initusercodehere  
}  
returnform;  
}  
//  
 
//  
 
publicChoiceGroupgetWeather_CG(){  
if(weather_CG==null){  
//writepre-initusercodehere  
weather_CG=newChoiceGroup
("u5929u6C14u7C7Bu578B",Choice.EXCLUSIVE);  
weather_CG.setLayout(ImageITEM类.LAYOUT_DEFAULT);  
weather_CG.setFitPolicy(Choice.TEXT_WRAP_DEFAULT);  
//选项框项的代码  
weather_CG.append("晴",null);  
weather_CG.append("阴",null);  
weather_CG.append("雨",null);  
weather_CG.append("雪",null);  
weather_CG.setSelectedIndex(0,true);  
//writepost-initusercodehere  
}  
returnweather_CG;  
}  
//  
 
 
 
 
publicDisplaygetDisplay(){  
returnDisplay.getDisplay(this);  
}  
 
publicvoidexitMIDlet(){  
switchDisplayable(null,null);  
destroyApp(true);  
notifyDestroyed();  
}  
 
publicvoidstartApp(){  
if(midletPaused){  
resumeMIDlet();  
}else{  
initialize();  
startMIDlet();  
}  
midletPaused=false;  
}  
 
publicvoidpauseApp(){  
midletPaused=true;  
}  
 
publicvoiddestroyApp(booleanunconditional){  
}  
}