Problems with a program...

[Adam Polak]

I have a couple of problems with the following problem.
The color for the circel and the ovaal objects are set to red but change when you add them both. Also if you start with circle you'll get ovaal out of it. I want them to co exist together...
If I change the place of the line in the Y-scale but not in the X-scale it becomes longer instead of moving.
Hope you can help!

 import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
public class hoofdstuk11test2 extends Applet implements ActionListener{
Button knop1, knop2, knop3, knop4, knop5, knop6;
TextField xInvoer, yInvoer;
public int yWaarde;
public int xWaarde;
Vorm vorm1, vorm2, vorm3;
Lijn lijn1, lijn2, lijn3;
Circel cir1, cir2, cir3;
Ovaal ov1, ov2, ov3;

public void init() {

setLayout(null);
resize(600,600);

knop1= new Button("vorm");
knop1.setBounds(10,10,40,20);
add(knop1);
knop1.addActionListener(this);

knop2= new Button("lijn");
knop2.setBounds(10,50,40,20);
add(knop2);
knop2.addActionListener(this);
knop3= new Button("cirkel");
knop3.setBounds(10,90,40,20);
add(knop3);
knop3.addActionListener(this);

knop4= new Button("Ovaal");
knop4.setBounds(10,130,40,20);
add(knop4);
knop4.addActionListener(this);

knop5= new Button("Driehoek");
knop5.setBounds(10,170,40,20);
add(knop5);
knop5.addActionListener(this);
knop6= new Button("Verplaats");
knop6.setBounds(10,210,40,20);
add(knop6);
knop6.addActionListener(this);

xInvoer = new TextField(2);
xInvoer.setBounds(200,25,75,25);
add(xInvoer);

yInvoer = new TextField(2);
  yInvoer.setBounds(350,25,75,25);
  add(yInvoer);
}

public void paint(Graphics g) {

vorm1.laatZien(g,Color.red);

lijn1.laatZien(g,Color.blue);

cir1.laatZien(g,Color.green);
ov1.laatZien(g,Color.yellow);

}


public void actionPerformed(ActionEvent event){

if (event.getSource()==knop1) vorm1 = new Vorm(60,30);

else if (event.getSource()==knop2) { 
lijn1 = new Lijn(100,30,100,100);
vorm1= lijn1;}

else if (event.getSource()==knop3) { 
cir1 = new Circel(300,300,100);
vorm1= cir1;}

else if (event.getSource()==knop4) { 
ov1 = new Ovaal(300,300,100);
vorm1= ov1;}

else if (event.getSource()==knop6){

xWaarde = Integer.parseInt(xInvoer.getText());
yWaarde = Integer.parseInt(yInvoer.getText());
vorm1.verplaats(xWaarde,yWaarde);

}

repaint();

}


}
class Vorm{
protected int x0, y0;
public Vorm() {}
public Vorm(int x, int y) {
x0= x;
y0= y;
}

public void verplaats(int dx, int dy){

x0= x0+ dx;
y0= y0+ dx;

}

public void laatZien(Graphics g, Color c) {
g.setColor(c);
for (int i= -2; i<3; i++)
g.drawLine(x0-2, y0+i, x0+2, y0+i);//WAT GEBEURT HIER
}
}
class Lijn extends Vorm{
private int x1, y1;

public Lijn(int x0, int y0, int x1, int y1){
super(x0, y0);
this.x1=x1;
this.y1=y1;
}

public void verplaats(int dx, int dy) {

//Super Methode voor verplaatsting
super.verplaats(dx,dy);

//Verplaatsing voor onderpunten
x1= x1+dx;
y1= y1+dy;


}

public void laatZien(Graphics g, Color c){
g.setColor(c);
g.drawLine(x0, y0, x1, y1);
}

}
class Circel extends Vorm{

protected int d0;

public Circel(int x0, int y0, int d){

super(x0, y0);
this.d0=d;
}


public void laatZien(Graphics g, Color c){
g.setColor(c);
g.fillOval(x0, y0, d0, d0);
}
}
class Ovaal extends Circel{

protected int d1;

public Ovaal(int x0, int y0, int d){

super(x0, y0, d);
this.d1=d/2;
}


public void laatZien(Graphics g, Color c){
g.setColor(c);
g.fillOval(x0, y0, d0, d1);
}
}
 

[Marilyn de Queiroz]

I'm seeing more than one problem. First of all I suggest that you initialize your vorm1, lijn1, cir1, and ov1. Maybe something like this in init():

vorm1 = new Vorm(0,0);
lijn1 = new Lijn(0,0,0,0);
cir1 = new Circel(0,0,0);
ov1 = new Ovaal(0,0,0);

This will help with the NullPointerExceptions.

Second, I think part of the problem is due to polymorphism. Try putting the
vorm1.laatZien( g ,Color.red );
line at the end of the print() method and see if that helps you get what you want.
[ February 16, 2003: Message edited by: Marilyn de Queiroz ]

[Marilyn de Queiroz]

If I change the place of the line in the Y-scale but not in the X-scale it becomes longer instead of moving.

class Vorm{

public void verplaats(int dx, int dy){

x0= x0+ dx;
y0= y0+ dx;

}

} 

Should this be

y0 = y0 + dy ;

??

[Adam Polak]

You are right in your second post but the first one doesn't make a difference...

[Adam Polak]

Anyone else who could help me out with this?

[Marilyn de Queiroz]

hmmm. That's odd. When I changed from

public void paint(Graphics g) {
    vorm1.laatZien(g,Color.red);
    lijn1.laatZien(g,Color.blue);
    cir1.laatZien(g,Color.green);
    ov1.laatZien(g,Color.yellow);
}

to

public void paint( Graphics g ) {
    lijn1.laatZien( g , Color.blue );
    cir1.laatZien( g , Color.green );
    ov1.laatZien( g , Color.yellow );
    vorm1.laatZien( g ,Color.red );
}

it made a big difference in the way the applet ran for me.

Are you using the appletviewer or a browser? If a browser, which one?

Vorm = form, Lijn = line, Circel = circle, and Ovaal = oval, right? What does laatZien mean? What does verplaats mean?