Graphics Movement?

[[Gandalf]]

I was trying to make an applet with graphics, and I know how to draw things, but how do I do movement? You can draw various things, but how do I make it update the screen multiple times? Here is what I was trying so far:

Java:

import java.awt.*; import java.applet.Applet; public class AppletGraphics6 extends Applet {                int i = 1;         public void paint(Graphics g)         {                 g.drawLine(1, 1, i, i);                 i += 1;                 paint (g);                 delay (500);         }                               public void delay(int milliSec)         {         try         {             Thread.sleep(milliSec);         } catch (Exception e)         {             System.err.println(e);         }     } }

Also, if someone could tell me how to do the same thing using Swing, or point me to somewhere that could help me. Thanks.

[wtd]

Java:

import javax.swing.*; import java.awt.*; public class AppletGraphics6 extends JApplet {           int i;    public void init()    {       i = 1;    }    public void paint(Graphics g)    {       g.drawLine(1, 1, i, i);       i += 1;       delay(500);       paint(g);    }           void delay(int milliSec)    {       try       {          Thread.sleep(milliSec);       }       catch (Exception e)       {          System.err.println(e);       }    } }

Does this work?

[[Gandalf]]

Indeed it does! Thanks wtd .

Anyone know where I can find a way to do this for an application?

*edit*
I am trying to set the colour of a drawn object throuhg g.setColor(), like so:

code:

g.setColor(white);

and I get a compile time error message - "cannot find symbol variable white". This happens for any colour I use.

[Hikaru79]

[Gandalf] wrote:

*edit*
I am trying to set the colour of a drawn object throuhg g.setColor(), like so:

code:

g.setColor(white);

and I get a compile time error message - "cannot find symbol variable white". This happens for any colour I use.

Well, what is white? It hasn't been defined, right? It's actually a static field of the Color class. So, try g.setColor(Color.white); . Should work ^_^ (You may need to import java.awt.Color if you haven't already)

[wtd]

Hikaru79 wrote:

[Gandalf] wrote:

*edit*
I am trying to set the colour of a drawn object throuhg g.setColor(), like so:

code:

g.setColor(white);

and I get a compile time error message - "cannot find symbol variable white". This happens for any colour I use.

Well, what is white? It hasn't been defined, right? It's actually a static field of the Color class. So, try g.setColor(Color.white); . Should work ^_^ (You may need to import java.awt.Color if you haven't already)

Could work if you use:

Java:

import static java.awt.Color.*;

[[Gandalf]]

I thought I tried that, but I guess I didn't since it worked...

I don't need to import those since I already have import java.awt.*.

[rizzix]

i advise against using static imports.. use it when absoloutly necessary... like when porting C API's to JAVA..

[[Gandalf]]

The ball will neither move nor appear in the proper spot... The start location should be what is passed to the constructor, and the ball should move according to move(). It works, but doesn't work properly .

Java:

import javax.swing.*; import java.awt.*; class Ball {         private int x, y;                 public Ball(int xStart, int yStart)         {                 x = xStart;                 y = yStart;         }                 public void move()         {                 x += 1;                 y += 1;         }                 public int getX()         {                 return x;         }                        public int getY()         {                 return y;         } } public class BallMovement extends JApplet {                Ball ball = new Ball(300, 300);         public static int maxx, maxy;         public void init()         {                 maxx = 600;                 maxy = 600;         }         public void paint(Graphics g)         {                 g.setColor(Color.white);                 g.drawOval(getX(), getY(), 10, 10);                 ball.move();                 g.setColor(Color.red);                 g.drawOval(getX(), getY(), 10, 10);                 delay(5);                 paint(g);         }                        public void delay(int milliSec)         {                 try                 {                         Thread.sleep(milliSec);                 }                 catch (Exception e)                 {                         System.err.println(e);                 }         } }

Thanks for any help.

*edit* Ok, so far I've figured out the problem is with my getX() and getY() methods, but why? how? hmm..

[Aziz]

Just one correction, ol' buddy...

Quote:

I don't need to import those since I already have import java.awt.*.

Don't assume this.

For example, at the top of my current project's file, I have these lines:

Java:

import javax.swing.*; import java.awt.*; import java.awt.event.*; import javax.swing.event.*;

I must have these lines. Yes, I have imported java.awt.* but that does not include all packages within that package. So if you're importing java.awt.* you're not importing Color's white member. You're including Color, but not importing it, you have to reference it. I hope that makes sense

[[Gandalf]]

Alright, but that's what the Color.<colour> is for, right? Since each colour is static...

How about my current program?

[Aziz]

Right. So you can use 'Color.white', but not just 'white'

[wtd]

Aziz wrote:

Right. So you can use 'Color.white', but not just 'white'

Unless you're using 1.5.x or greater and use a static import.

[rizzix]

once again refrain from doing that

[wtd]

Well, first off... it's good to understand things, even if understanding them leads you to avoid them (sometimes especially in those cases).

Second... why? What's so wrong with using static imports?

[rizzix]

its counter-java way of getting things done. In java everything is part of an instance of a class or part of the class it self.. (with the only exception being primitives).. that's the philosophy!.. and refrain from code that will eventually result in YOU trying to figure out where those constants were once defined (maybe some time in the future..). this is especially troublesome when you have "more than one" of those static imports.

After all "Color.white" is a lot more meaningful than "white" alone.