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for loop working 2 - 4 times

Virendrasinh Gohil wrote:

Megs Maquito wrote:Hmmm. that seemed to do the trick here's the result:

L is 20 i is 0
.......
L is 140 i is 13
outside the for loop
.................

Question is: why would i need to put something outside the for loop? is the i % == 2 somehow telling the class to repaint itself or is it the sequence after the JFrame declaration in main() method? I have other classes that have a for loop that does not have a statement outside the for loop and works perfectly. Here's an example:
....
...
...

No, putting print statement outside of for loop will not prevent executing the paintComponent() method multiple times. I just mentioned that to show you that it's not the "for" loop which is creating problem but it is the event of request to repaint the JPanel. And that is what exactly happened when you re-executed the application. Whenever there is a repaint (either manual or system generated) event, your paintComponent() will get executed.

I could put the for loop in the main method but I want the drawing to be repainted if i resize the JFrame, thus I put the for loop in the paintComponent() method.

Now, if you want to recalculate the length of line on every paintComponent() method, you need to calculate using actual numbers (and not just keep increasing the line using for loop). That means, if the frame/panel is reduced in size, the line size should use new width/heigth values to decrease the line length. This way, let it be multiple repaint event to occur for same window, it will always calculate the lineLength correctly.

OMG you're a genius. However, having the spiral recalculate will entail some heavy duty math (at least for me

) I was able to create what I wanted whilst not growing with the frame. I did what you earlier suggested (that is to put the lineLength calculation outside the paintComponent()). And here's the full code:

/A program that draws a sprial line
import java.awt.Graphics;
import java.awt.Color;
import javax.swing.JPanel;
import javax.swing.JFrame;
public class SpiralLine extends JPanel{
private static enum Direction {DOWN, LEFT, UP, RIGHT};
private int [] lineLength = new int [21];
private int x, y, x1, x2, y1, y2;
public void paintComponent(Graphics g){
super.paintComponent(g);
//starting coordinates at the middle of panel
x = getWidth() / 2;
y = getHeight() / 2;
x1 = x;
x2 = x;
y1 = y;
y2 = y;
g.setColor(Color.RED);
Direction nextDirection = Direction.DOWN;
for (int i = 0; i < lineLength.length; ++i){
switch (nextDirection){
case DOWN: y2 = y2 + lineLength[i];
g.drawLine(x1, y1, x2, y2);
y1 = y2;
nextDirection = Direction.LEFT;
break;
case LEFT: x2 = x2 - lineLength[i];
g.drawLine(x1, y1, x2, y2);
x1 = x2;
nextDirection = Direction.UP;
break;
case UP: y2 = y2 - lineLength[i];
g.drawLine(x1, y1, x2, y2);
y1 = y2;
nextDirection = Direction.RIGHT;
break;
case RIGHT: x2 = x2 + lineLength[i];
g.drawLine(x1, y1, x2, y2);
x1 = x2;
nextDirection = Direction.DOWN;
default: break;
}//end of switch
}//end of for loop
}//end of paintComponet
//method that generates lineLength which increases every other drawing
public void generateLineLength(){
lineLength[0] = 20;
for (int i = 1; i < lineLength.length; ++i){
if (i % 2 == 0)
lineLength[i] = lineLength [i - 1] + 20;
else lineLength [i] = lineLength [i - 1];
System.out.println(""+lineLength[i - 1]);
}//end of for loop
}//end of generateLineLength
public static void main (String[] args){
SpiralLine panel = new SpiralLine();
panel.generateLineLength();
JFrame application = new JFrame();
application.add(panel);
application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
application.setSize(250,250);
application.setVisible(true);
}//end of main
}//end of class

Yeah I know, it may seem very elementary for you

. I'm just starting out. Thanks so much for your help.

Virendrasinh Gohil = javaGenius(int x);
public int javaGenius (int n){int intelligence = n * infinity; return intelligence};

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