Java Question...

[mirkazemisaman]

Alright, I am quiet a novice in java programming. I tried to search on google for source code to upload images and tried them. But I am still getting errors when trying to run my program. So as a last resort I came here to ask you guys since I know I can always get solutions here...
Here is my sample code (sorry, for some reason the message board takes out my bracket indentations):

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

public class TestImage extends JFrame
{
private Image picture;
private Graphics gfx;
private Toolkit toolkit = Toolkit.getDefaultToolkit();
public TestImage()
{
picture = toolkit.getImage("fivecards.gif");
gfx = this.getGraphics();
gfx.drawImage(picture, 0, 0, this);
this.setSize(500, 500);
this.show();
}
public static void main(String [] args)
{
TestImage window = new TestImage();
}
}

The image is in the same directory as the file and the code compiles, but i get a run-time error (NullPointerException in "main") at lines 15 and 21 (1st line is the 1st import statement). Can someone enlighten me as to what I am doing wrong????

thanx in advance.

[mirkazemisaman]

Alright, I am quiet a novice in java programming. I tried to search on google for source code to upload images and tried them. But I am still getting errors when trying to run my program. So as a last resort I came here to ask you guys since I know I can always get solutions here...
Here is my sample code (sorry, for some reason the message board takes out my bracket indentations):

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

public class TestImage extends JFrame
{
private Image picture;
private Graphics gfx;
private Toolkit toolkit = Toolkit.getDefaultToolkit();
public TestImage()
{
picture = toolkit.getImage("fivecards.gif");
gfx = this.getGraphics();
gfx.drawImage(picture, 0, 0, this);
this.setSize(500, 500);
this.show();
}
public static void main(String [] args)
{
TestImage window = new TestImage();
}
}

The image is in the same directory as the file and the code compiles, but i get a run-time error (NullPointerException in "main") at lines 15 and 21 (1st line is the 1st import statement). Can someone enlighten me as to what I am doing wrong????

thanx in advance.

[Janak Parekh]

I avoid graphics programming nowadays, but the line 21 error is simply chaining to the line 15 error, which is

gfx.drawImage(picture, 0, 0, this);

It means that "picture" is null. Put a test right above it to confirm. As to why it's null, it means the toolkit.getImage() call is failing. Why, I don't know, I don't have enough data to be able to tell.

--janak

[JonMisurda]

Actually, what's null is the Graphics object. You can't draw on the screen before the window is shown. This code should work (i.e. It works for me):

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

public class TestImage extends JFrame
{
	private Image picture; 
	private Graphics gfx;
	private Toolkit toolkit = Toolkit.getDefaultToolkit();
	
	public TestImage()
	{
		picture = toolkit.getImage("fivecards.gif");
		this.setSize(500, 500);
		this.show();
	}

	public void paint(Graphics gfx) {
		gfx.drawImage(picture, 0, 0, this);
	}

	public static void main(String [] args)
	{
		TestImage window = new TestImage();
	}
}

Hope that helps,

Jon

[Janak Parekh]

Originally Posted by JonMisurda

Actually, what's null is the Graphics object. You can't draw on the screen before the window is shown. This code should work (i.e. It works for me):

D'oh! ops: I stand corrected. Like I said, I've been avoiding AWT/Swing programming for some time now, and any Swing programming I do now is strictly UI stuff...

--janak

[mirkazemisaman]

thanx, that makes sence. I thought my Image object was some how null and I oculdn't figure it out...

[mirkazemisaman]

I am going to get started learning some sort of 3D programming (I only do Java). Which of these two is better for a beginner:

Java 3D API
OpenGL

[maximus]

DirectX :wink: