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Thread: Problem with threads

  1. #1
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    Default Problem with threads

    My StarScape is still not running on its own after adding threading. I still have to click or resize to see the next frame of animation.

    new StarScape:
    // 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 = 1000;
      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();
        t.start();
      }
     
      public void run() 
      {
        Graphics g = getGraphics();
        do 
        {
          paint(g);
          repaint();
        }while (key == "");
      }
     
      public void paint(Graphics g)
      {
        g.setColor(Color.black);
        g.fillRect(0,0,800,600);// make the background black
        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
    // 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);//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);//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
    Last edited by Spidey1980; August 19th, 2011 at 10:42 PM.


  2. #2
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    Default Re: Problem with threads

    My StarScape is still not running on its own after adding threading
    What is the purpose of multithreading for your program?

    Anyway, this code snippet is wrong:

      public void start() 
      {
        Thread t = new Thread();
        t.start();
      }

    You created a new empty thread then start it. This is useless because the thread does nothing.

    Following is a proper way:


      public void start() 
      {
        Thread t = new Thread(this);
        t.start();
      }

    immutable objects
    Last edited by ha.minh.nam; December 4th, 2011 at 07:32 PM.

  3. The Following User Says Thank You to ha.minh.nam For This Useful Post:

    Spidey1980 (August 20th, 2011)

  4. #3
    Super Moderator Norm's Avatar
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    Default Re: Problem with threads

    Also get rid of the call to getGraphics and to paint. The call to repaint will automatically cause a call to be made to your paint method with a Graphics object.

  5. The Following User Says Thank You to Norm For This Useful Post:

    Spidey1980 (August 20th, 2011)

  6. #4
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    Default Re: Problem with threads

    I musta been tired last night. Thread(this) gave me a "variable this not found in StarScape.class" so I had removed it.

    however this morning I tried it and it works perfectly. I guess I just can't type that late at night.

    Thank you issue solved check out my new show off thread i'm about to start......

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