package stumng;
import javax.swing.UIManager;
import java.awt.*;
/**
  *<p>Title:</p>
  *<p>Description:</p>
  *<p>Copyright:Copyright(c)2005</p>
  *<p>Company:</p>
  *@author not attributable
  *@version 1.0
  */
public class stuMngApp{
   boolean packFrame=false;
   //Construct the application
   public stuMngApp(){
     stuInfMng frame=new stuInfMng();   //实例化一个框架
     //Validate frames that have preset sizes
     //Pack frames that have userful prefered size info,e.g.from their layout
   if(packFrame){
      frame.pack();
   }
   else{
     frame.validate();
   }
   //Center the window
   Dimension screenSize=Toolkit.getDefaultToolkit().getScreenSize();   //得到屏幕的大小
   Dimension frameSize=frame.getSize();   //得到框架的尺寸
   if(frameSize.height>screenSize.height){
      frameSize.height=screenSize.height;
   }
   if(frameSize.width>screenSize.width){
      frameSize.width=screenSize.width;
   }
   frame.setTitle("欢迎进入学生管理系统");  //对框架的标题
   frame.setLocation((screenSize.width-frameSize.width)/2,(screenSize.height-frameSize.height)/2);
   frame.setVisible(true);  //设置框架的可见方式
}


//Main method
public static void main(String[] args){
  try{
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());  //设置图形界面的外观
  }
catch(Exception e){
  e.printStackTrace();
  }
new stuMngApp();
 }
}



我用eclipse编译的时候不成功，应该是stuInfMng frame=new stuInfMng();   中的stuInfMng类没定义，那么应该怎么去定义这个类呢？