我在cmd中运行java class文件后，跳出Exception in thread "main" java.lang.NosuchmethodError:main 请问这是怎么回事？？是java文件有问题吗？？我的java文件为：
import java.awt.*;
import java.applet.*;
import java.util.*;

public class BorderLayoutDemo extends Applet
{
public void init()
{
setLayout(new BorderLayout());

add(new Button("This is arross the top"),
BorderLayout.NORTH);
add(new Label("The message is on the bottom"),
BorderLayout.SOUTH);
add(new Button("Left"),BorderLayout.WEST);
add(new Button("Right"),BorderLayout.EAST);
String message="This is the message in the Center!";
add(new TextArea(message),BorderLayout.CENTER);
}
}