BUG Community

Hi,

I’m trying to learn Java in preparation for getting a Bug and have gotten stuck when it comes to understanding how graphics work.

I wrote a program that randomly selects a start and ending point on a 2D grid. Then, it unleashes thousands of ‘bugs’ (cast from the bug class) which move about quasi-randomly trying to find the end point.

Basically, I’d like to simply be able to draw out that 2D grid and illustrate each bug as a colored circle. Could someone explain how that could be done in my code, or point to a sample program which does something similiar?

Thanks!

CLASS 1:
public class Bug {

/ Initial Variables /
        String name;
        private int xPos;            //X-Position variable
        private int yPos;            //Y-Position variable
        private int i = 0;            //Indexing Variable
        private float xPosRandom = (float) Math.random();
        private float yPosRandom = (float) Math.random();

/ This method is used to pull in the initial starting position of the given
        Bug object /
        public void setInitialize(BugMain2 HiveMind)    {

// Pull Initial Starting Coordinates
        xPos = HiveMind.getxStartPosition();
        yPos = HiveMind.getxStartPosition();

}

/ This method is used to randomly simulate movement used to simulate movement /
        public void moveBug(BugMain2 HiveMind)    {

// Modification of the X-Position Variable
        if (Math.random() >= xPosRandom)    {
            ++xPos;
        }    else    {
            --xPos;
        }

// Modification of the Y-Position Variable
        if (Math.random() >= yPosRandom)    {
            ++yPos;
        }    else    {
            --yPos;
        }

// Final Checks for Arena Size Constraints (i.e. the bug can't leave the field)
        if (xPos > HiveMind.getxMaxValue())    {    --xPos;        }
        if (yPos > HiveMind.getyMaxValue())    {    --yPos;        }

if (xPos < HiveMind.getxMinValue())    {    ++xPos;        }
        if (yPos < HiveMind.getyMinValue())    {    ++yPos;        }

System.out.println(name  ": "  i  " "  getxPos()  " "  getyPos());
        i++;

if (xPos  HiveMind.getxEndPosition() && yPos  HiveMind.getyEndPosition())    {
            HiveMind.setIsFinished(true);
            System.out.println("");
            System.out.println("Solution Found By: " + name);
            System.out.println("Number of Attempts: " + i);
            System.out.println("Percent Over Optimal: " + (float) 100  Math.abs(Math.max(HiveMind.getxEndPosition(), HiveMind.getyEndPosition()) - i)/Math.max(HiveMind.getxEndPosition(), HiveMind.getyEndPosition()));
        }

}

/ Used to get the xPos variable /
        public int getxPos()    {
            return xPos;
        }

/ Used to get the yPos variable /
        public int getyPos()    {
            return yPos;
        }

/ Used to set the Bug's Name /
        public void setName(String nameString)    {
            name = nameString;
        }

CLASS 2:
import javax.swing.;
import java.awt.;
import java.awt.geom.;

public class BugMain2 {

/ Initialization of Important Parameters /
        int xStartPosition = 0;            //Initialization of starting positions
        int yStartPosition = 0;

int xEndPosition = 87;            //Initialization of ending position (puzzle solution)
        int yEndPosition = 66;

int xMaxValue = 100;            //Initialization of max and min values for the arena
        int yMaxValue = 100;
        int xMinValue = 0;
        int yMinValue = 0;

int NumberInSwarm = 1000;

Boolean IsFinished = false;

public static void main(String[] args)    {

// Variables and Objects
        BugMain2 HiveMind = new BugMain2();
        HiveMind.go(HiveMind);

}

public void go(BugMain2 HiveMind)    {

// Creation of Bug(s)
        Bug[] Bugs = new Bug[NumberInSwarm];

// Initialization
        for (int i=0; i < NumberInSwarm; i++)    {
            Bugs[i] = new Bug();
            Bugs[i].setName("BuG_" + i);
        }

// Begin Race
        while (IsFinished != true)    {

for (int j=0; j < NumberInSwarm ; j++)    {
            Bugs[j].moveBug(HiveMind);
            if (IsFinished == true)    {    break;    }

}

}

}

public int getxStartPosition()    {
            return xStartPosition;
        }

public int getyStartPosition()    {
            return yStartPosition;
        }

public int getxEndPosition()    {
            return xEndPosition;
        }

public int getyEndPosition()    {
            return yEndPosition;
        }
        public int getxMaxValue()    {
            return xMaxValue;
        }

public int getyMaxValue()    {
            return yMaxValue;
        }

public int getxMinValue()    {
            return xMinValue;
        }

public int getyMinValue()    {
            return yMinValue;
        }

public void setIsFinished(Boolean IsFound)    {
            IsFinished = IsFound;
        }

}

Hey,

I definately want to get back to you on this question although I am leaving for class in 5 minutes so here is the 10 second answer.

1) Check out the java.awt.Canvas and java.awt.Graphics2D classes
2) You can’t use javax.swing stuff, that is not available on the BUG, only the java.awt.*; classes are

Searching my del.icio.us I came up with these, don’t know if they helpful but at some point in time I tagged them with AWT and Java

http://java.sun.com/developer/onlineTraining/aw…
http://home.cogeco.ca/ve3ll/jatutorg.htm
http://www.javaworld.com/javaworld/jw-07-1996/j…

Longer answer later!

Thanks for the quick reply, I’m definitely looking forward to your next one!

I still am confused about the graphics class (probably because I am so new to this), so forgive the dumb question, but are there graphics objects? All examples seem to show a method accepting a graphics object as an input, but I never see where it is instantiated, or even what java libraries are needed. If you could, in your next response, could you shed some light on that?

Thanks!

If you get a chance, can you post some sample code / point to a tutorial?

Thanks!

Yea I definitely will I didn’t mean to leave you hanging but I’m in the middle of midterms this week (4 midterms 20 page paper a lot of regular homework = no time). Next week I will get a chance since I am on spring break, sorry for the wait.

No problem at all! Good luck with the tests!

Thanks for the sample code!

I’ve got it up and running and have been playing around with it for a bit now. FYI: Eclipse didn’t like a few lines like involving packaging and importing, so I commented them out.

I have two quick questions for you though …

1. When I run the code in Eclipse, the frame pops up as it should … However, when I try to x-it out, it wont go away. I’ve had to resort to Ctrl-Alt-Delete. Why is that?

2. I can’t seem to figure out how the paint method it ExampleCanvas is being called! I’ve looked everywhere, but I never see it called, not even in the constructors … I must be missing something simple, what is it??

Thanks again!

The paint method in ExampleCanvas gets called with the frame.show(); line in the main method. Every component that you add to a container gets its paint method called then. Even though Eclipse likes to cross that line out as depreciated, it is not and you need that line.

As for stopping the window, not sure, but if you hit the red square on the console in Eclipse it will close easily.

The packaging depends on how you setup your project. I like to make things broken up into a lot of packages because I like to reuse my code as much as possible, I’d rather write twice as much if I can use it again because no matter how one off a project I think it is, I always seem to use some of it later.

Here is a good reference on the paint method and updating in AWT. I’m working on casting a bunch of BUGs around the screen and updating them.

http://java.sun.com/products/jfc/tsc/articles/p…

I have to say that my example is not exactly their perfect use case, but I’m working on it. They say that you should not call the paint class explicitly for a number of reasons (basically, it can fail) and use the repaint() method. That brings up the point of breaking up what you are drawing into objects. It would be tempting to just throw it all in as one Canvas object that needs to get drawn, but then each time it needs to be updated, everything needs to be redrawn. If you make it a number of objects then only the updated objects need to be repainted which hopefully will reduce flicker. Now I’m thinking should each BUG be an object or should I make an object that paints all of them like I did for the gridmarkers? If they are all to be updated every time, then one object is the best route for minimum overhead, but if only some are going to be updated each time than making each one an object would be better. That is kind of up to you.

Thanks John,

I am far from an authority on AWT, my GUI programming was all Qt/C+ and GTK/C++ prior to the BUG, but Sun has a lot of good reference material, if only I took the time to read it!