Thread: Icons not visable?

I'm making it so that users can switch the theme of the icons for the JOptionPane (java defult, windows defult, and a custom one). the method works fine inside the class its declared in but when calling it outside of the class I'm getting this error:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at GUI.setImageIcon(GUI.java:286)
        at Updater.checkForUpdates(Updater.java:28)
        at GUI.actionPerformed(GUI.java:172)
        at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
        at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
        at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Sour
ce)
        at java.awt.Component.processMouseEvent(Unknown Source)
        at javax.swing.JComponent.processMouseEvent(Unknown Source)
        at java.awt.Component.processEvent(Unknown Source)
        at java.awt.Container.processEvent(Unknown Source)
        at java.awt.Component.dispatchEventImpl(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
        at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
        at java.awt.Container.dispatchEventImpl(Unknown Source)
        at java.awt.Window.dispatchEventImpl(Unknown Source)
        at java.awt.Component.dispatchEvent(Unknown Source)
        at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
        at java.awt.EventQueue.access$000(Unknown Source)
        at java.awt.EventQueue$3.run(Unknown Source)
        at java.awt.EventQueue$3.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Sour
ce)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Sour
ce)
        at java.awt.EventQueue$4.run(Unknown Source)
        at java.awt.EventQueue$4.run(Unknown Source)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Sour
ce)
        at java.awt.EventQueue.dispatchEvent(Unknown Source)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
        at java.awt.EventDispatchThread.run(Unknown Source)

The method setImageIcon if defined in the class GUI. here it is:

public ImageIcon setImageIcon(String iconSet) {
		ImageIcon iconType = null;
		if (iconStyle.equals("Emotocons")) {
			if (iconSet.equals("inform")) {
				iconType = happyface;
			}
			if (iconSet.equals("error")) {
				iconType = angryface;
			}
			if (iconSet.equals("warning")) {
				iconType = anotherface;
			}
		}
 
		if (iconStyle.equals("java_defult")) {
			if (iconSet.equals("inform")) {
				iconType = javaInfo;
			}
			if (iconSet.equals("error")) {
				iconType = javaError;
			}
			if (iconSet.equals("warning")) {
				iconType = javaWarning;
			}
		}
 
		if (iconStyle.equals("windows_defult")) {
			if (iconSet.equals("inform")) {
				iconType = windowsInfo;
			}
			if (iconSet.equals("error")) {
				iconType = windowsError;
			}
			if (iconSet.equals("warning")) {
				iconType = windowsWarning;
			}
		}
 
		return iconType;
	}

Now when I call that outside of the class GUI is when i get there error. I'm calling it in the class Updater. here it is:

if (command.equalsIgnoreCase("update")) {
			JOptionPane.showMessageDialog(null, "There is a more recent version. " +
					"\nPlease download it on the website!", "Free RS Membership Updater", JOptionPane.WARNING_MESSAGE, g.setImageIcon("warning"));
		} else {
			JOptionPane.showMessageDialog(null, "You have the most recent version!", 
					"Free RS Membership Updater", JOptionPane.INFORMATION_MESSAGE, g.setImageIcon("inform"));
		}

I did try this before and it said I didnt have the icons set visible but I rewrote the method since then and now I cant seem to get it to work.. please help!