3 replies to this topic

[JaseR33]

It gets an error message on the line -

Oval shape = new Oval (x, y, d, d);

I narrowed it down to the "d's" in it.

Here is the code:

import java.awt.Color;
import javax.swing.JFrame;
import java.util.Scanner;

public class shapes
{

public static void main(String[] args) {

JFrame win = new JFrame("usershape");
win.setBounds(10, 10, 400, 300);
win.setLayout(null);
win.setVisible(true);

Scanner scanner = new Scanner(System.in);
System.out.println ("Enter the X and Y coordinates and area of a circle: ");
int x = scanner.nextInt();
int y = scanner.nextInt();
int a = scanner.nextInt(); // a is the area

double r = (Math.sqrt (a) / 3.14) ; // r is the radius
double d = (r * 2); // d is the diameter

Oval shape = new Oval(x, y, d, d);
shape.setBackground(Color.black);

win.add(shape, 0);
win.repaint();
}

}

[wim DC]

• Classes must always begin with a Capital Letter.
  
• It doesn't know the Oval class because i don't think it exists...

If I had to draw an oval i'd do it this way:

import java.awt.*;

import javax.swing.*;

import java.util.Scanner;


public class Shapes [B][COLOR="red"]extends JPanel [/COLOR][/B]{

    int x,y,d;

    JFrame frame;


    public Shapes(){

        [B][COLOR="red"]super();[/COLOR][/B]

        frame = new JFrame("userscreen");

        frame.add(this);

        frame.setSize(800,600);


        askUser();

    }


    private void askUser(){

        Scanner scanner = new Scanner(System.in);

        System.out.println("Enter the X and Y coordinates and area of a circle: ");

        x = scanner.nextInt();

        y = scanner.nextInt();

        int a = scanner.nextInt(); // a is the area

        System.out.println("scanning done");

        d = (int) Math.round(Math.sqrt(a*4/Math.PI)); // d is the diameter


        frame.setVisible(true);        

    }


    public static void main(String[] args) {

        Shapes shape = new Shapes();

    }


  [B] [COLOR="red"] @Override

    public void paint(Graphics g) {

        super.paint(g);

        g.setColor(Color.RED);

        g.fillOval(x,y,d,d);

    }[/COLOR][/B]

}

Note that setting the frame visible will automatically call the paint method.
If you need to manually call the paint method you can use:
paint(this.getGraphics());

2nd note: the area you give in is not in cm² but pixels². So if you give an area of let's say 50. You'll barely see an oval. Area of 5000 gives a nice circle ;)

[JaseR33]

Yeah , the Oval class definately exists, thats why I dont understand why it wont draw it.
Oh and how do I put my code in a little blue box like you do on here? Sorry for being a stupid newbie :)

here is the Oval class-

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

/** Oval Supplier Class
* Author: David D. Riley
* Date: April, 2004
*/
public class Oval extends JComponent {

/** post: getX() == x and getY() == y
* and getWidth() == w and getHeight() == h
* and getBackground() == Color.black
*/
public Oval(int x, int y, int w, int h) {
super();
setBounds(x, y, w, h);
setBackground(Color.black);
}

/** post: this method draws a filled Oval
* and the upper left corner of the bounding rectangle is (getX(), getY())
* and the oval's dimensions are getWidth() and getHeight()
* and the oval's color is getBackground()
*/
public void paint(Graphics g) {
g.setColor( getBackground() );
g.fillOval(0, 0, getWidth()-1, getHeight()-1);
paintChildren(g);
}

}

[wim DC]

Ahhhhhh it's your own class :D That explains why i coudn't find it on the internet .

Posting code in the box = putting the code in code tags. like

 here goes my code [/ code] without a space between / and code.  You can also press the # button.



Okay why doesn't it work? The Oval constructor expects int, int, int, int  and you give it int, int, double, double.


try [code]Oval shape = new Oval(x, y, (int) d, (int) d);

Note: casting double to int will not round the value but just drop the decimal part 1.999 would become 1 and not 2. You can do

 int value = (int) Math.round(1.999);

if you like to round.