J2ME学习笔记：Alert控件的使用【原创】

首先我们要知道：Alert是一个显示等待或错误信息的屏幕类，其构造方法如下：Alert（标题，初始内容，图像，类型）如Alert info = new Alert("Alert","This is a Alert Example!",img,AlertType.INFO);

以下给出一个代码：

import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
import javax.microedition.lcdui.*;

public class Alert extends MIDlet implements CommandListener {

private Command exitCommand;
private Command alertCommand;
private TextBox tb;

public Alert()
{
   exitCommand = new Command("Exit",Command.EXIT,1);
   alertCommand = new Command("Alert",Command.SCREEN,1);
   tb = new TextBox("Terry","Alert Example",15,0);
   tb.addCommand(exitCommand);
   tb.addCommand(alertCommand);
   tb.setCommandListener(this);

   Display.getDisplay(this).setCurrent(tb);
}
   public Alert(String string, String string2, Image img, AlertType info) {
   // TODO Auto-generated constructor stub
}
protected void startApp() throws MIDletStateChangeException
    {
//   Display.getDisplay(this).setCurrent(tb);
  
}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException
{
  

}

protected void pauseApp()
{
  

}
public void commandAction(Command c, Displayable d) {
   //如果触发alertCommand按钮，则显示Alert屏幕
   if(d == tb && c == alertCommand){
    Image img;
    try{
     img = Image.createImage("/2.png");
    }
    catch(java.io.IOException e)
    {
     img = null;
     System.out.println("img is load...");
    }
    //创建一个Alert屏幕对象
    Alert info = new Alert("Alert","This is a Alert Example!",img,AlertType.INFO);
   
   }
  
  
}

 

}