Note: Buttons.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

F:\myjava>javac Icons.java
Icons.java:11: cannot find symbol
symbol  : variable EXIT_CLOSE_EXIT
location: class javax.swing.JFrame
                setDefaultCloseOperation(JFrame.EXIT_CLOSE_EXIT);
                                               ^
Icons.java:16: cannot find symbol
symbol  : class JButtons
location: class Icons
                        buttons[i]=new JButtons(icon);
                                       ^
Note: Icons.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
2 errors

import javax.swing.*;

public class Icons extends JFrame
{
  JButton[] buttons=new JButton[24];
  
  public Icons()
  {
    super("Icons");
    setSize(335,318);
    setDefaultCloseOperation(JFrame.EXIT_CLOSE_EXIT);
    JPanel pane =new JPanel();
    ImageIcon icon=new ImageIcon("icon.gif");
    for(int i=0;i<24;i++)
    {
      buttons[i]=new JButtons(icon);
      pane.add(buttons[i]);
    }
    setContentPane(pane);
    show();
  }
  public static void main(String [] args)
  {
    Icons ike=new Icons();
  }
}