Java - setting an image icon to an application window

[wan2no]

I've been trying for the longest while to get it done but failed miserably. i had

public class test extends JFrame
{
public JFrame win;

public test()
{
win.setIconImage(Toolkit.getDefaultToolkit.getImage("name of image.gif"));

setVisible(true);
}
}

I also tried

public class test extends JFrame
{
public test()
{
setIconImage(Toolkit.getDefaultToolkit.getImage("name of image.gif"));

setVisible(true);
}
}

none of the 2 worked. Can someone please help me?