New working theaded non-system-crippling Starscape

Thank you everyone for all your help. Here is the final polished version:

StarScape.java

Code java:

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// starscape.java
// by Jon Crawford
import Star.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.geom.*;
import java.io.*;
import java.math.*;
import java.lang.*;
 
public class StarScape extends JApplet implements Runnable
{
  final int maxStars = 500;
  String key = "";
  String valid;
  int index;
  double myX;
  double myY;
  int myRadius;
  int myLayer;
  int rectX;
  int rectY;
  int rectXX;
  int rectYY;
  private long myStarDelay = 20;
  Star stars[] = new Star[maxStars+1];//make 1000 star objects
 
  public void init()
  {
    for (index = 0; index < maxStars; index++)
    {      
      stars[index] = new Star();//fill array with stars
    }//end for 
  }//end init
 
  public void start() 
  {
    Thread t = new Thread(this);
    t.start();
  }
 
  public void run()
  {
    do 
    {
      repaint();
      try 
      {
        Thread.sleep(40);
      } 
      catch (InterruptedException e)
      {
      }
    }while (key == "");
  }
 
  public void paint(Graphics g)
  {
    g.setColor(Color.black);
    g.fillRect(0,0,800,600);// make the background black, erase all previous stars
    for (index = 0; index < maxStars; index++) 
    {
      stars[index].moveStar();//move the star
      valid = stars[index].starValid();
      if (valid == "false")
      {//is star out of bounds?
        stars[index].resetStar();
      }  
      myX = stars[index].getStarX();
      myY = stars[index].getStarY();
      myRadius = stars[index].getStarRadius();//get data agian because star was moved
      myLayer = stars[index].getStarLayer();//layer just denotes shade of star. 
      if (myLayer == 3) 
      {
        g.setColor(Color.white);
      }else if (myLayer == 2) 
      {
        g.setColor(Color.lightGray);
      }else if (myLayer == 1) 
      {
        g.setColor(Color.darkGray);
      }else 
      {
        g.setColor(Color.white);//these set color based on layer
      }
      rectX = (int)(myX) - myRadius + 399;
      rectY = (int)(myY) - myRadius + 299;
      rectXX = myRadius * 2;
      rectYY = myRadius * 2;//set up the new star I mean rectangle
      g.fillOval(rectX, rectY, rectXX, rectYY);//draw star
    }//end for
  }//end paint
 
}//end starscape

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Star.java

Code java:

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// star.java
// by Jon Crawford
package Star;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.geom.*;
import java.io.*;
import java.math.*;
 
public class Star {
 
  private final int starSpeed = 1;
  private final int starRadius = 1;
  private final int starSteps = 0;
  private final float[] invalidValues = new float[]{ -399f, -299f, 399f, 299f, 0f, 0f};
  private String isValid = "false";
  private double starAngle;
  private double starField[] = new double[9];
  private double starX;
  private double starY;
  private int starLayer;
 
  public Star()
  {
    starX = Math.random() * 200 - 99;//star starts in a small square
    starY = Math.random() * 200 - 99;//in the center
    starLayer = (int)(Math.random() * 3 + 1);//random layer
    starAngle = (Math.sqrt((starX * starX)+(starY * starY)));//calculate the hypotenuse
    starField[0] = starX;//set data to star's arrary
    starField[1] = starY;//this is for current position
    starField[2] = starX / starAngle * starSpeed;//these set the next position
    starField[3] = starY / starAngle * starSpeed;//this is reltive current position
    starField[4] = starLayer;//back, mid, or foreground layer
    starField[5] = starRadius;//star starting size
    starField[6] = starSpeed * starLayer;//the starting speed
    starField[7] = starSteps;//star has taken 0 steps, every 5 steps star grows and speeds up
    starField[8] = starAngle;//store the hypotenuse
  }//end constructor
 
  public void moveStar() 
  {//mutator method
    System.out.println("") ;    
    starField[0] = starField[0] + starField[2];//next position becomes the curent position 
    starField[1] = starField[1] + starField[3];       
    starField[2] = starField[0] / starField[8] * starField[6];//new next position
    starField[3] = starField[1] / starField[8] * starField[6];
    starField[7] = starField[7] + 1;//increment steps
    if (starField[7] / 5 == (int)(starField[7] / 5) && starField[5] < 20)
    {//if star has taken 5 steps
      starField[5] = starField[5] + 1;//increment size
      starField[6] = starField[6] + 1;//increment speed
    }//end if      
  }//end moveStar
 
  public void resetStar()
  {//resetStar method
    starX = Math.random() * 200 - 99;//set new starting position
    starY = Math.random() * 200 - 99;
    starLayer = (int)(Math.random() * 3 + 1);//new random layer
    starAngle = (Math.sqrt((starX * starX)+(starY * starY)));//calculate new hypotenuse
    starField[0] = starX;//set data to star's array
    starField[1] = starY;//same as default constructor
    starField[2] = starX / starAngle * starSpeed;
    starField[3] = starY / starAngle * starSpeed;
    starField[4] = starLayer;
    starField[5] = starRadius;
    starField[6] = starSpeed * starLayer;
    starField[7] = starSteps;
    starField[8] = starAngle;
  }//end resetStar
 
  public String starValid()
  {//isValid method
    if(starField[0] > invalidValues[0] && starField[1] > invalidValues[1] && starField[0] < 
 
invalidValues[2] && starField[1] < invalidValues[3])
    {//in bounds?
      isValid = "true";
    }else
    {//out of bounds
      isValid = "false";
    }//end if
    return isValid;
  }//end is valid
 
  public int getStarX() 
  {//get method
    return (int)(Math.round(starField[0]));
  }//end getStarX
 
  public int getStarY() 
  {//get method
    return (int)(Math.round(starField[1]));
  }//end getStarY
 
  public int getStarRadius() 
  {//get method
    return (int)(Math.round(starField[5]));
  }//end getStarRadius
 
  public int getStarLayer() 
  {//get method
    return (int)(Math.round(starField[4]));
  }//end getStarLayer
 
}//end class star

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edit: It has now been running for an hour with no problems.

Small comments.
Several of your variables are defined at the class level but are only used at in one method. They could be defined local to that method.

Code :

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 if (valid == "false")

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Use the equals() method when comparing Strings.
However this variable should be a boolean, not a String.


Should the starting shape be a square or a circle?

LOL I don't think you can make a circle out of a 2x2 square of pixels. If you Talking about the fillRect in my code, that's the background. Easier than erasing each star, and visually there is no difference to painting the whole canvas black each time, or erasing each star individually. On older systems that ran QB, It did look better to erase each star individually.

Sure, I could polish it some more but I'm done with that. I just thought, If I can convert that from QB to java learning java on my own (not paying some college my hard earned cash), then I can make anything with java.

Java is good, it makes me learn good technique and style. Have self-taught myself programming, I had no style whatsoever in my QB programs.

Quote:

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LOL I don't think you can make a circle out of a 2x2 square

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This is the square I was talking about:

Code :

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    starX = Math.random() * 200 - 99;//star starts in a small square
    starY = Math.random() * 200 - 99;//in the center

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Change this logic to chose the x,y combinations that are in a circle vs a small square.

What I'm talking about there is that I do not want a star to start close to the edge to immediately move out of range. So that the Stars actually have a little more time on screen, I start them near the center. The above line of code starts the star randomly somewhere inside a box with a size -99,-99 to 99,99. However the full grid is -399,-299 to 399,299. When drawing a star this is converted to a 0,0 to 800,600 grid.

The screen and virtual grid are both rectangular in shape. The Star it self is round(oval).

Code :

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__________
|         |
|   __    |
|  |__|   |
|         | 
|_________|

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As the above awful text art shows, the square in the center is where I start my stars. The stars move out from there toward the edge of the big square, then they start again at a new random location inside the center square. I would love the center starting area to be a circle, but the math for that would be more complicated then the vector math I use to define the direction each star moves.

Quote:

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I would love the center starting area to be a circle

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There is a very simple way to filter out the random numbers that are not in a circle.
Try this:

Code :

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          do {    // get in a circle <<<<<<<<<<<<<<<<<
            myX = Math.random() * 200 - 99;//set new starting position 
            myY = Math.random() * 200 - 99;
          } while(Math.sqrt(myX*myX + myY*myY) > 99); // reject if outside

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Thats great! I love it. You took the vector math even further. WOW.

So basically use the logarithm to find the distance x,y is from 0,0 and reject anything that is further than 99 pixels away from 0,0.