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Thread: Why does this not work?

  1. #1
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    Default Why does this not work?

    Okay so I started my starscape again from scratch. This time I created a class of stars and defined two methods, moveStar and resetStar.

    Then I created and applet that first checks to see if the stars are out-of-bounds, which they all are from start. It then calls resetStar and moveStar. Both these methods put the data into a public array. Then the applet erases the old star, puts the newPos into the holder for the oldPos, and then draws the star at the newPos. then it loops through the index, and the repeats via a do...while loop until the user closes the window or clicks back.

    I messed with it until it compiled with no errors, and now I'm getting runtime dirty regions errors. I then commented old everything from the first fillRect and threw in some printlns, but even with no drawing commands I still got the dirty regions error. This is becoming a little frustrating.

    the Star class:

    // star.java
    // by Jon Crawford
     
    import java.util.*;
     
    public class Star {
     
      private int ctrl;
      private int starSpeed = 4;
      private int starRadius = 1; 
      private int adjustedSpeed;
      private int adjustedRadius;
      private int xPos;
      private int yPos;
      private int steps;
      private double angle;
      private int starColor;
      private int ins;
      private float star[] = new float[8];
      Random rand = new Random();
     
      Star(){
        starColor = 0;
        star[7] = 0;
        for (int ctrl = 0; ctrl < 8; ctrl++) {
          star[ctrl] = 0;
        }//end for
      }//end constructor 1 
      Star(int color){
        starColor = color;
        for (ctrl = 0; ctrl < 6; ctrl++) {
          star[ctrl] = 0;
        }//end for
      }//end constuctor 2
     
      public void resetStar(float index,float starField[][]) {
        steps = rand.nextInt(10);
        starColor = rand.nextInt(3);
        adjustedRadius = starRadius;
        if (starColor == 1) {
          adjustedSpeed = starSpeed / 4;
        }
        else if (starColor == 2) {
          adjustedSpeed = starSpeed / 2;
        }
        else if (starColor == 3) {
          adjustedSpeed = starSpeed;
        }//end if
        xPos = rand.nextInt(399) - 199;
        yPos = rand.nextInt(299) - 149;
        if (xPos == 0) {
          xPos = 1;
        }
        if (yPos == 0) {
          yPos = 1;
        }
        angle = (Math.sqrt((xPos * xPos)+(yPos * yPos)));
        star[0] = xPos;
        star[1] = yPos;
        star[2] = xPos;
        star[3] = yPos;
        star[4] = starColor;
        star[5] = adjustedRadius;
        star[6] = adjustedSpeed;
        star[7] = steps;
        star[8] = (float)angle;
        ins = (int)(index);
        for (ctrl = 0; ctrl < 7; ctrl++) {
          starField[ins][ctrl] = star[ctrl];
        }//end for
      }//end reset
     
      public void moveStar(float index, float starField[][]) {
        ins = (int)(index);
        for (ctrl = 0; ctrl < 7; ctrl++) {
          star[ctrl] = starField[ins][ctrl];
        }//end for
        star[3] = star[1] / star[8] * star[6];
        star[4] = star[2] / star[8] * star[6];
        star[7]++;
        if (star[7] / 5 == (int)(star[7] / 5) && star[5] < 10) {
          star[5]++;
          star[6]++;
        }//end if
        ins = (int)(index);
        for (ctrl = 0; ctrl < 7; ctrl++) {
          starField[ins][ctrl] = star[ctrl];
        }//end for
      }//end moveStar
    }//end class star

    StarScape Applet:
    // starscape.java
    // by Jon Crawford
     
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    import java.awt.geom.*;
     
    public class StarScape extends JApplet {
      public void paint(Graphics g){
        String i = "";
        int x = 0;
        int y = 0;
        int w = 799;
        int v = 599;
        int ind = 0;
        int maxStars = 100;
        int dX = 0;
        int dY = 0;
        Star field[] = new Star[maxStars];
        float starField[][] = new float[maxStars][8];
        g.setColor(Color.black);
        g.fillRect(x,y,w,v);
        do {
          for (float index = 0; index < maxStars; index++) {
            ind = (int)(index);
            if (starField[ind][1] <= 1 || starField[ind][2] <= 1 || starField[ind][1] >= 799 || starField[ind][2] >= 599) {
              field[ind].resetStar(index, starField);
            }//end if
            field[ind].moveStar(index, starField);
            dX = (int)(starField[ind][1] + 199);
            dY = (int)(starField[ind][2] + 149);
            g.setColor(Color.black);
            x = (int)(dX - starField[ind][5]);
            y = (int)(dY - starField[ind][5]);
            w = (int)(dX + starField[ind][5]);
            v = (int)(dY + starField[ind][5]);
    //debugger:        System.out.println("\t\t " + x + "\t " + y + "\t " + w + "\t " + v);
            g.fillRect(x,y,w,v);
            if (starField[ind][4] == 1) {
              g.setColor(Color.white);
            }
            else if (starField[ind][4] == 2) {
              g.setColor(Color.lightGray);
            }
            else if (starField[ind][4] == 3) {
              g.setColor(Color.darkGray);
            }//end if
            starField[ind][1] = starField[ind][3];
            starField[ind][2] = starField[ind][4];
            dX = (int)(starField[ind][1] + 199);
            dY = (int)(starField[ind][2] + 149);
            x = (int)(dX - starField[ind][5]);
            y = (int)(dY - starField[ind][5]);
            w = (int)(dX + starField[ind][5]);
            v = (int)(dY + starField[ind][5]);
    //debugger:        System.out.println("\t\t " + x + "\t " + y + "\t " + w + "\t " + v);
            g.fillRect(x,y,w,v);
          }//end for
        }while (i == "");//end while
      }//end paint
    }//end starscape

    The runtime console output:
    Microsoft Windows [Version 6.1.7601]
    Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
     
    C:\Users\Jon>cd..\
     
    C:\Users>cd..
     
    C:\>cd JSource/Stars
     
    C:\JSource\Stars>AppletViewer StarScape.html
    Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
            at StarScape.paint(StarScape.java:28)
            at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
     
            at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:713)
     
            at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:6
    93)
            at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(System
    EventQueueUtilities.java:125)
            at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
            at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641)
            at java.awt.EventQueue.access$000(EventQueue.java:84)
            at java.awt.EventQueue$1.run(EventQueue.java:602)
            at java.awt.EventQueue$1.run(EventQueue.java:600)
            at java.security.AccessController.doPrivileged(Native Method)
            at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessCo
    ntrolContext.java:87)
            at java.awt.EventQueue.dispatchEvent(EventQueue.java:611)
            at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
    ad.java:269)
            at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
    java:184)
            at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
    ad.java:174)
            at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
     
            at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
     
            at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
            at StarScape.paint(StarScape.java:28)
            at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
     
            at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:713)
     
            at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:6
    93)
            at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(System
    EventQueueUtilities.java:125)
            at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
            at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641)
            at java.awt.EventQueue.access$000(EventQueue.java:84)
            at java.awt.EventQueue$1.run(EventQueue.java:602)
            at java.awt.EventQueue$1.run(EventQueue.java:600)
            at java.security.AccessController.doPrivileged(Native Method)
            at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessCo
    ntrolContext.java:87)
            at java.awt.EventQueue.dispatchEvent(EventQueue.java:611)
            at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThre
    ad.java:269)
            at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.
    java:184)
            at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
    ad.java:174)
            at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
     
            at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
     
            at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
     
    C:\JSource\Stars>

    Please help!
    Last edited by Spidey1980; August 11th, 2011 at 11:07 AM. Reason: Grammatical


  2. #2
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Why does this not work?

    What line is StarScape:28?
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  3. #3
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    Default Re: Why does this not work?

    the second g.setColor(Color.black); is at line 28.

    I do get the first black rectangle (the one that sets my background color.)
    Last edited by Spidey1980; August 11th, 2011 at 11:05 AM. Reason: grammatical

  4. #4
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    Default Re: Why does this not work?

    This thread is dead this code is outdtated already

  5. #5
    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: Why does this not work?

    ...so did you solve your problem?
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