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Thread: Help with simple applet.

  1. #1
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    Default Help with simple applet.

    All the applet does is print a brick wall. I've got it made with using for loops, but now I'd like to get it done using while and do while loops, but I can't seem to get it working using while loops, and I haven't even attempted doing it using do while loops. Any suggestions? All it does is print the first column for some reason.

    This is my fully working "for loop" version:

    package ton_of_bricks;
     
    import java.applet.Applet;
    import java.awt.*;
     
    public class Ton_of_bricks_for extends Applet{
     
       private static final long serialVersionUID = 1L;
     
       public static final int START_X = 0;
       public static final int START_Y = 0;
       public static final int BRICK_WIDTH = 60;
       public static final int BRICK_HEIGHT = 30;
       public static final int DISPLAY_WIDTH = 600;
       public static final int DISPLAY_HEIGHT = 600;
       public static final int GAP = 10;
     
       public void init(){
    	   resize(DISPLAY_WIDTH, DISPLAY_HEIGHT);
    	   setBackground(Color.darkGray);
       }
     
       public void paint(Graphics g){
     
       	   int x = START_X;
       	   int y = START_Y;
     
       	   g.setColor(Color.RED); 
     
       	   for (int row = 1; row <= DISPLAY_WIDTH; row++){ //while row is less than windows width, increase rows
     
       			for (int col = 1; col <= DISPLAY_HEIGHT; col++){ //while col is less than windows height, increase cols 
     
       				g.fillRect (x, y, BRICK_WIDTH, BRICK_HEIGHT); //drawing bricks
     
       				x += BRICK_WIDTH + GAP; //generates columns
       			}
     
       			if (row%2 == 0)
       				x = START_X;
       			else
       				x = START_X - BRICK_WIDTH/2 - GAP/2; //offsets bricks  
     
       				y += BRICK_HEIGHT + GAP; //generates rows
     
       	   } //end for(rows)
       } //end pain
    } //public class ton_of_bricks_for

    This is my broken "while loop" version, where only the first column is working:

    package ton_of_bricks;
     
    import java.applet.Applet;
    import java.awt.*;
     
    public class Ton_of_bricks_while extends Applet{
     
       private static final long serialVersionUID = 1L;
     
       public static final int START_X = 0;
       public static final int START_Y = 0;
       public static final int BRICK_WIDTH = 30;
       public static final int BRICK_HEIGHT = 15;
       public static final int DISPLAY_WIDTH = 600;
       public static final int DISPLAY_HEIGHT = 600;
       public static final int GAP = 5;
     
       public void init(){
    	   resize(DISPLAY_WIDTH, DISPLAY_HEIGHT);
    	   setBackground(Color.darkGray);
       }	
     
       public void paint(Graphics g){
     
       	   int x = START_X;
       	   int y = START_Y;
     
       	   g.setColor(Color.RED); 
     
       	   int row = 1;
       	   int col = 1;
     
       	   while (row <= DISPLAY_WIDTH){ //while row is less than windows width, increase rows
       		   row++;
     
       	   		while (col <= DISPLAY_HEIGHT) //while col is less than windows height, increase cols 
       	   			col++;         	 
     
       	   			g.fillRect (x, y, BRICK_WIDTH, BRICK_HEIGHT); //drawing bricks
     
       				x += BRICK_WIDTH + GAP; //generates columns
     
     
       			if (row%2 == 0)
       				x = START_X;
       			else
       				x = START_X - BRICK_WIDTH/2 - GAP/2; //offsets bricks  
     
       				y += BRICK_HEIGHT + GAP; //generates rows
     
       	   } //end for(rows)
       } //end pain
    }//public class ton_of_bricks_for

    Any suggestions on fixing the problem? I would also appreciate it if anyone could point me in the right direction of starting the "do while" version as well. Thank you!


  2. #2
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    Default Re: Help with simple applet.

    After the inner (col) loop finishes what value will col have? Will it ever be less than DISPLAY_HEIGHT again?
    Improving the world one idiot at a time!

  3. #3
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    Default Re: Help with simple applet.

    Sorry I forgot a closing brace for the while. Only the first row is displayed, rather than first column. Still can't figure it out

    while (row <= DISPLAY_WIDTH){ //while row is less than windows width, increase rows
       		   row++;
     
       	   		while (col <= DISPLAY_HEIGHT) //while col is less than windows height, increase cols 
       	   			col++;         	 
     
       	   			g.fillRect (x, y, BRICK_WIDTH, BRICK_HEIGHT); //drawing bricks
     
       				x += BRICK_WIDTH + GAP; //generates columns
       	   }

  4. #4
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    Default Re: Help with simple applet.

    Did you read my post?
    Did you answer my questions?
    Improving the world one idiot at a time!

  5. #5
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    Default Re: Help with simple applet.

    Quote Originally Posted by Junky View Post
    Did you read my post?
    Did you answer my questions?
    Well, it will have the value of +1 since it's incrementing, right? and it's supposed to loop only if it's less than the height, so I would hope it would be less again. Sorry, really bad at while loops

  6. #6
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    Default Re: Help with simple applet.

    Why would it be less again? Values of variables do not magically change. Run this code and see if you can understand the problem.
    int max = 5;
    int row = 0;
    int col = 0;
    while(row < max) {
            while(col < max) {
                System.out.print("*");
                col++;
            }
            System.out.println();
            System.out.println(col);
            system.out.print("Is col less than max: ");
            System.out.println(col < max);
    }
    How many rows get printed?
    Improving the world one idiot at a time!

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