hi, how to add a graphic component , say a line2D, to a swing?

[noobplus]

hi, how to add a graphic component , say a line2D, to a swing?
my graphic line method is ..

void paintComponent ()
{
Graphics2D g1 = new Graphics2D (g);
g1.drawLine(1,1,10,10);
}

and I have initialized Graphics using "import java.awt.Graphics2D" and geometry using "import java.awt.geom.*"
but where to call the method "paintComponent()" is it in the method "public static void main(String args[])" or in another method, and Does my codings show error in graphics initialization(Graphics2D g1 = new Graphics (g);) ?

and I always get the error "your graphics2D object "g" has NULL value

thx
regards
dhilip

[Norm]

What is the code you posted supposed to do? It does not make sense.
What is the datatype of the paintComponent arg that is passed on line 1?
What is the method's name?

[DarrylBurke]

Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

db

[noobplus]

What is the code you posted supposed to do? It does not make sense.
What is the datatype of the paintComponent arg that is passed on line 1?
What is the method's name?

actually, my doubt is I don't know, where to use the method"paintComponent"
regards
dhilip

[noobplus]

Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

db

im sorry bro, i typed wrong codings.. now i updated it.
Actually i typed "void (paintComponent g){" instead of "void paintComponent(){"

[DarrylBurke]

im sorry bro, i typed wrong codings.. now i updated it.
Actually i typed "void (paintComponent g){" instead of "void paintComponent(){"

Too much trouble to actually go through the tutorial, huh?

db

[kjkrum]

actually, my doubt is I don't know, where to use the method"paintComponent"

It's defined in JComponent, so you would override it in a class that extends JComponent.

You never call it yourself. The Swing event thread does that for you.

[noobplus]

It's defined in JComponent, so you would override it in a class that extends JComponent.

You never call it yourself. The Swing event thread does that for you.

thx, and how do we initialize graphics into the method "paintComponent()" ? that would help out my project. my project submission date is coming soon next week.

upto my knowledge,

public class abc extends JComponent
{
void paintComponent(Graphics g) 
{
Graphics output = new Graphics (g);
output.drawLine(1,1,10,10);
}
}

// and one more doubt.. can the class that extends JComponent be a public class? (JComponent can work alone? or needs to be attached to a JFrame? If so, should it be initialized into the class extending JFrame? )
regards
dhilip

[Norm]

Why try to create an unusable Graphics object (line 5)when there is good one passed to the method?

[DarrylBurke]

Better go through the whole Trail: Creating a GUI With JFC/Swing (The Java™ Tutorials)

db

[noobplus]

Why try to create an unusable Graphics object (line 5)when there is good one passed to the method?

So, what about , shall i do this new code?

public class abc extends JComponent
{
void paintComponent(Graphics g)
{
//Graphics output = new Graphics (g);
g.drawLine(1,1,10,10);  //output.drawLine changed to g.drawLine
}
}

[Norm]

Have you compiled and executed it? What happens?

[noobplus]

Have you compiled and executed it? What happens?

hi,
I added a main method to it in eclipse. (like given below)

import javax.swing.*;
import java.awt.*;
public class framecomp extends JComponent
{
protected void paintComponent(Graphics g)
{
//Graphics output = new Graphics (g);
g.drawLine(1,1,10,10);  //output.drawLine changed to g.drawLine
}
public static void main(String args[])
{
	framecomp f = new framecomp();
	f.paintComponent(null)// this line asks for a proper argument. and what arguments should i give?
}
}

ive mentioned the comment in the main method.
regards
dhilip

[Norm]

What happens when you execute that code?

Did you read the link posted in post#10? Especially this part:
http://docs.oracle.com/javase/tutori...ing/index.html

It looks like you are making code up instead of following the recommendations shown in the tutorial

[Tolls]

As Darryl suggests, I think the OP needs to sit down and go through the whole Swing tutorial.
Currently they're just making stuff up and hoping it works, with no idea at all how Swing fits together.

[noobplus]

What happens when you execute that code?

Did you read the link posted in post#10? Especially this part:
Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

It looks like you are making code up instead of following the recommendations shown in the tutorial

there was no class demonstrations.. and yet I found the title "Painting in Swing " paint() and repaint() are called in the class extending the Frame..
Painting in AWT and Swing
paint is in package "container" think so,..
thx for the link,
so should we initialize graphics in main() method?

regards
dhilip

[noobplus]

As Darryl suggests, I think the OP needs to sit down and go through the whole Swing tutorial.
Currently they're just making stuff up and hoping it works, with no idea at all how Swing fits together.

could u give me a demo java class drawing a line in swing and that would help my a lot plz
regards
dhilip

[Norm]

In the tutorial there is code: SwingPaintDemo2 that draws a String:
g.drawString("This is my custom Panel!",10,20);
replace that with:
g.drawLine(1,1,100,100);

[noobplus]

In the tutorial there is code: SwingPaintDemo2 that draws a String:
g.drawString("This is my custom Panel!",10,20);
replace that with:
g.drawLine(1,1,100,100);

working on that. thx
regards
dhilip

[Tolls]

Better go through the whole Trail: Creating a GUI With JFC/Swing (The Java™ Tutorials)

db

could u give me a demo java class drawing a line in swing and that would help my a lot plz
regards
dhilip

No.
Go through the link above provided by Darryl.
You will have to do this if you want to work with Swing GUIs.
You clearly don't know enough about it at the moment. Providing code will simply make things worse.