How can I assign image file name from Main() class

Question

I am trying to create library class which will be accessed and used by different applications (with different image files to be assigned). So, what image file to call should be determined by and in the Main class.
Here is the Main class
import org.me.lib.MyJNIWindowClass;
public class Main {
public Main() {
public static void main(String[] args) {
MyJNIWindowClass mw = new MyJNIWindowClass();
mw.s = "clock.gif";
And here is the library class
package org.me.lib;
public class MyJNIWindowClass {
public String s;
ImageIcon image = new ImageIcon("C:/Documents and Settings/Administrator/Desktop/" + s);
public MyJNIWindowClass() {
JLabel jl = new JLabel(image);
JFrame jf = new JFrame();
jf.add(jl);
jf.setVisible(true);
jf.pack();
I do understand that when I am making reference from main() method to MyJNIWindowClass() s first initialized to null and that is why clock could not be seen but how can I assign image file name from Main() class for library class without creating reference to Main() from MyJNIWindowClass()? As I said, I want this library class being accessed from different applications (means different Main() classes).
Thank you.

Answer 1

Your problem is one of timing. Consider this simple example.
public class Example {
    public String s;
    private String message = "Hello, " + s;
    public String toString() {
        return message;
    public static void main(String[] args) {
        Example ex = new Example();
        ex.s = "world";
        System.out.println(ex.toString());
}When this code is executed, the following happens in order:
1. new Example() is executed, causing an object to constructed. In particular:
2. field s is given value null (since no value is explicitly assigned.
3. field message is given value "Hello, null"
4. Back in method main, field s is now given value "world", but that
doesn't change message.
5. Finally, "Hello, null" is output.
The following fixes the above example:
public class Example {
    private String message;
    public Example(String name) {
        message = "Hello, " + name;
    public String toString() {
        return message;
    public static void main(String[] args) {
        Example ex = new Example("world");
        System.out.println(ex.toString());
}