Thread: How to read from all files in a directory & plot the contents?

/*PS: This topic has something to do with Java graphics as well*/
Hi,
I'm working on a star map (graphics program), the final output of the program is similar to:
http://nifty.stanford.edu/2009/reid-.../starchart.jpg

These are the steps i follow:
Step 1
Write a method to convert between star coordinate system to the Java picture coordinate system.
The star coordinate system has (0,0) in the center, and −1 and 1 as the extremes.
The Java graphics coordinate system has (0,0) as the top-left corner, and positive numbers extend down and right up to the screen size.
---->diagram: http://i45.tinypic.com/2z4fgog.jpg

Step 2
Read the contents of the star-data.txt file, and plot the stars on a Java graphics window. Use a black background, and plot the stars as white circles.

star-data.txt contains info on 3,526 stars, this number appears on the first line of the file.
Subsequent lines has the following fields:
-x, y coordinates for stars (in star coordinate system, e.g. 0.512379, 0.020508)
- Henry Draper number (just a unique identifer for the star)
-magnitude (or brightness of star)
-names of some stars. A star may have several names.

Step 3
Vary the size of the circles to reflect their magnitude. Since brighter stars have smaller magnitude values, you will need to calculate the circle radius, say, 10/(magnitude + 2).

Step 4
Read from all files in constellation folder, and plot them on top of the stars.
Each file contains pairs of star names that make up lines in the constellation.


I have already done Steps 1 - 3.
I'm using files :
-StarApp.java as my application class that has main() method
-StarJFrame.java ,this class creates the window & defines its properties & behavior
-StarJPanel.java ---> heres the code, for this class, below
-Star.java -----> heres the code, for this class, below

 [B]StarJPanel.java[/B]
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.Scanner;
 
public class StarJPanel extends JPanel implements ActionListener {
 
	private Star[] stars;
	private Timer timer;
 
	public StarJPanel() {
 
		setBackground(Color.black);
		timer = new Timer(5, this);
 
		stars = getArrayOfStars();
 
		timer.start();
	}
 
	private Star[] getArrayOfStars() {
 
		// This method reads the Stars data from a file and stores it in the stars array.
 
		int howMany = Integer.parseInt(Keyboard.readInput());
		Star[] stars = new Star[howMany];
 
		for (int i = 0; i < stars.length; i++) {
			String input = Keyboard.readInput();
			Scanner fields = new Scanner(input);
			double x = Double.parseDouble(fields.next());
			double y = Double.parseDouble(fields.next());
			int draper = Integer.parseInt(fields.next());
			double magnitude = Double.parseDouble(fields.next());
			String namesString = "";
			String[] names = {};
			if (fields.hasNext()) {
				namesString = fields.nextLine();
				names = namesString.trim().split("; ");
			}
			stars[i] = new Star(x, y, draper, magnitude, names);
		}
		return stars;
	}
 
	public void actionPerformed(ActionEvent e) {
		repaint();
	}
 
	public void paintComponent(Graphics g) {
		super.paintComponent(g);
 
		for(int i = 0; i < stars.length; i++) {
			stars[i].coordinateToPixel(stars[i].getX(), stars[i].getY());
 
			stars[i].drawStar(g);
		}
	}
}

[B]Star.java[/B] 
import java.awt.*;
import javax.swing.*;
 
public class Star {
 
	private double x, y;		// coordinates of star
	private int draper;			// Henry Draper number (unique identifier)
	private double magnitude;	// Magnitude (brightness) of star
	private String[] names;		// Star name(s) - not always present
	private int newX;
	private int newY;
	private int size;
 
	public Star( double x, double y, int draper, double magnitude, String[] names ) {
		this.x = x;
		this.y = y;
		this.draper = draper;
		this.magnitude = magnitude;
		this.names = names;
 
		size = (int)(10/(magnitude + 2));
	}
	public void coordinateToPixel(double x, double y) {
		newX = (int) ( (x + 1) * 350);
		newY = (int) ( (y - 1) * -350);
	}
	public void drawStar(Graphics g) {
		g.setColor(Color.white);
		g.drawOval( newX, newY, size, size);
	}
	public int getNumberOfNames() {
		return names.length;
	}
	public double getX() {
		return x;
	}
	public double getY() {
		return y;
	}
}

As you can see I have done:
Step 1: in Star class, with method: coordinateToPixel(double x, double y)
Step 2: in StarJPanel class with method: private Star[] getArrayOfStars()
(PS: I'm also using Keyboard class to read lines from the stars.txtfile)
Step 3: in Star class, with method: drawStar(Graphics g), where size = (int)(10/(magnitude + 2));

Please tell me if I have done 3 steps without confusing & incoherent code, I guess I have written the code differently from what ppl write. Somehow thats how we were taught to write. For me, my way gets a bit confusing sometimes!!

Now I'm left stuck with Step 4.
I have a folder where all my StarApp, StarJPanel, etc files are & a folder called Constellation
Inside constellation folder I have files that contain pairs of star names that make up lines in the constellation.
--Heres the constellation folder & star-data.txt file:
Constellations & star-data.rar


Although I'm thinkin i can use below code to read contents in files & use g.drawLine somewhere in StarJPanel. But I'm not sure how to find same names of stars in constellation files with names in the already set array from star-data & then join the coordinates with g.drawLine ???

import java.io.*;
 
public class reader {
	public static void main(String args[]) throws Exception {
		FileReader fr = new FileReader("Constellation/....");         /** Don't know what to put in ....... **/
		BufferedReader br = new BufferedReader(fr);
		String s;
 
		while((s = br.readLine()) != null) {
			System.out.println(s);
 
		}
 
		fr.close();
	}
}

Not sure how Step 4 is done please guide me.
By the way, I'm using textpad as my editor & complier.
So I have to go: Tools > Run in parameters i put: StarApp < star-data.txt inorder to load the Stars into screen.