Exception in thread main java.lang.NoClassDefFoundError: MyFirstframe(wrong name:MyFirstframe )

我的程序如下：
import javax.swing.JFrame;
public class MyFirstFrame extends JFrame {
public static void main(String[] args){
MyFirstFrame frame = new MyFirstFrame();
frame.setVisible(true);
}
public MyFirstFrame() {
super();
setTitle("我的窗体");
setBounds(100,100,500,375);
getContentPane().setLayout(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
高手给解决一下，谢了。

Exception EOleSysError in module 英语作文，主题：in th park Realistic novel in the 18th century on June 5th和in June Christmas in the 13th Month nothing in thé world 是什么意思？ Report ranks China 6th in overall strength 怎么翻译？ 谁能告诉我feminism in 17th century 在英国 The film was released on 11th July in China Fashions in America before the 19th century_____those of Egland.