Reading files when entered in parameter box

I use a program called JPad pro when running a program it has a parameter box. My program currently runs a file called graphics which contains the data to create some shapes in a GUI. I would like a method to modify this, so that i can enter the file i.e "graphics.txt" etc. or other data files straight into the parameter box when running the program. Any other suggestions are also welcome.

import java.io.*;
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
import java.util.*;

public class Proto1 extends JComponent{

private static final int WIDTH=400;
private static final int HEIGHT=300;

private ArrayList shapelist = new ArrayList();
public Proto1(){

this.setPreferredSize(new Dimension(WIDTH,HEIGHT));
this.setBorder(new LineBorder(Color.red,10));

try{
String s;
BufferedReader in = new BufferedReader(new FileReader ("graphics.txt"));
while(!(s=in.readLine()).equals("END"))
{
StringTokenizer st = new StringTokenizer(s);

String tok;
tok = st.nextToken();

if(tok.equals("LINE"))
{
shapelist.add(new Line2D.Float(
Integer.parseInt(st.nextToken()),
Integer.parseInt(st.nextToken()),
Integer.parseInt(st.nextToken()),
Integer.parseInt(st.nextToken())));
}
else if(tok.equals("CIRCLE"))
{
shapelist.add(new Ellipse2D.Double(
Integer.parseInt(st.nextToken()),
Integer.parseInt(st.nextToken()),
Integer.parseInt(st.nextToken()),
Integer.parseInt(st.nextToken())));
}
}

in.close();
}catch(IOException e){ System.out.println(e.getMessage());}
}

/* The paintComponent method is called whenever the frame is refreshed. */
public void paintComponent(Graphics g){

super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g; // g is a Graphics2D object
for(int i=0;i< shapelist.size();i++)
{
Shape shape = (Shape) shapelist.get(i);
g2.setPaint(Color.blue);
g2.draw(shape);
g2.fill(shape);
repaint();
}

}

public static void main( String [] args ){

JFrame jWindow = new JFrame("Prototype 1");
jWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jWindow.getContentPane().add(new Proto1(),BorderLayout.CENTER);
jWindow.pack();
jWindow.setVisible(true);

}

}