Java Applet Error

I'm using jdk7 and I get this error when I compile Exception in thread "main" java.lang.Error: Unresolved compilation problem: at First.main(First.java:16)

Java Code:

import javax.io.*;
import javax.awt.*;
import javax.lang.*;
import javax.applet.*;
import javax.net.*;
import javax.util.*;
import javax.swing.JApplet;
import javax.swing.JFrame;

public class First extends JApplet {

public void init() {
getContentPane().add(new JLabel("Applet!"));

[code]....