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How do I import a image from my computer in my java program? [duplicate]

I have a JPanel to which I'd like to add JPEG and PNG images that I generate on the fly.
All the examples I've seen so far in the Swing Tutorials, specially in the Swing examples use ImageIcons.
I'm generating these images as byte arrays, and they are usually larger than the common icon they use in the examples, at 640x480.
Is there any (performance or other) problem in using the ImageIcon class to display an image that size in a JPanel?
What's the usual way of doing it?
How to add an image to a JPanel without using the ImageIcon class?
Edit: A more careful examination of the tutorials and the API shows that you cannot add an ImageIcon directly to a JPanel. Instead, they achieve the same effect by setting the image as an icon of a JLabel. This just doesn't feel right...

If you are using JPanels, then are probably working with Swing. Try this:
BufferedImage myPicture = ImageIO.read(new File("path-to-file"));
JLabel picLabel = new JLabel(new ImageIcon(myPicture));
add(picLabel);
The image is now a swing component. It becomes subject to layout conditions like any other component.

Here's how I do it (with a little more info on how to load an image):
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
public class ImagePanel extends JPanel{
private BufferedImage image;
public ImagePanel() {
try {
image = ImageIO.read(new File("image name and path"));
} catch (IOException ex) {
// handle exception...
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this); // see javadoc for more info on the parameters
}
}

Fred Haslam's way works fine. I had trouble with the filepath though, since I want to reference an image within my jar. To do this, I used:
BufferedImage wPic = ImageIO.read(this.getClass().getResource("snow.png"));
JLabel wIcon = new JLabel(new ImageIcon(wPic));
Since I only have a finite number (about 10) images that I need to load using this method, it works quite well. It gets file without having to have the correct relative filepath.

I think there is no need to subclass of anything. Just use a Jlabel. You can set an image into a Jlabel. So, resize the Jlabel then fill it with an image. Its OK. This is the way I do.

You can avoid rolling your own Component subclass completely by using the JXImagePanel class from the free SwingX libraries.
Download

JLabel imgLabel = new JLabel(new ImageIcon("path_to_image.png"));

You can subclass JPanel - here is an extract from my ImagePanel, which puts an image in any one of 5 locations, top/left, top/right, middle/middle, bottom/left or bottom/right:
protected void paintComponent(Graphics gc) {
super.paintComponent(gc);
Dimension cs=getSize(); // component size
gc=gc.create();
gc.clipRect(insets.left,insets.top,(cs.width-insets.left-insets.right),(cs.height-insets.top-insets.bottom));
if(mmImage!=null) { gc.drawImage(mmImage,(((cs.width-mmSize.width)/2) +mmHrzShift),(((cs.height-mmSize.height)/2) +mmVrtShift),null); }
if(tlImage!=null) { gc.drawImage(tlImage,(insets.left +tlHrzShift),(insets.top +tlVrtShift),null); }
if(trImage!=null) { gc.drawImage(trImage,(cs.width-insets.right-trSize.width+trHrzShift),(insets.top +trVrtShift),null); }
if(blImage!=null) { gc.drawImage(blImage,(insets.left +blHrzShift),(cs.height-insets.bottom-blSize.height+blVrtShift),null); }
if(brImage!=null) { gc.drawImage(brImage,(cs.width-insets.right-brSize.width+brHrzShift),(cs.height-insets.bottom-brSize.height+brVrtShift),null); }
}

There shouldn't be any problem (other than any general problems you might have with very large images).
If you're talking about adding multiple images to a single panel, I would use ImageIcons. For a single image, I would think about making a custom subclass of JPanel and overriding its paintComponent method to draw the image.
(see 2)

JPanel is almost always the wrong class to subclass. Why wouldn't you subclass JComponent?
There is a slight problem with ImageIcon in that the constructor blocks reading the image. Not really a problem when loading from the application jar, but maybe if you're potentially reading over a network connection. There's plenty of AWT-era examples of using MediaTracker, ImageObserver and friends, even in the JDK demos.

I'm doing something very similar in a private project I'm working on. Thus far I've generated images up to 1024x1024 without any problems (except memory) and can display them very quickly and without any performance problems.
Overriding the paint method of JPanel subclass is overkill and requires more work than you need to do.
The way I do it is:
Class MapIcon implements Icon {...}
OR
Class MapIcon extends ImageIcon {...}
The code you use to generate the image will be in this class. I use a BufferedImage to draw onto then when the paintIcon() is called, use g.drawImvge(bufferedImage); This reduces the amount of flashing done while you generate your images, and you can thread it.
Next I extend JLabel:
Class MapLabel extends Scrollable, MouseMotionListener {...}
This is because I want to put my image on a scroll pane, I.e. display part of the image and have the user scroll around as needed.
So then I use a JScrollPane to hold the MapLabel, which contains only the MapIcon.
MapIcon map = new MapIcon ();
MapLabel mapLabel = new MapLabel (map);
JScrollPane scrollPane = new JScrollPane();
scrollPane.getViewport ().add (mapLabel);
But for your scenario (just show the whole image every time). You need to add the MapLabel to the top JPanel, and make sure to size them all to the full size of the image (by overriding the GetPreferredSize()).

This answer is a complement to #shawalli's answer...
I wanted to reference an image within my jar too, but instead of having a BufferedImage, I simple did this:
JPanel jPanel = new JPanel();
jPanel.add(new JLabel(new ImageIcon(getClass().getClassLoader().getResource("resource/images/polygon.jpg"))));

Create a source folder in your project directory, in this case I called it Images.
JFrame snakeFrame = new JFrame();
snakeFrame.setBounds(100, 200, 800, 800);
snakeFrame.setVisible(true);
snakeFrame.add(new JLabel(new ImageIcon("Images/Snake.png")));
snakeFrame.pack();

You can avoid using own Components and SwingX library and ImageIO class:
File f = new File("hello.jpg");
JLabel imgLabel = new JLabel(new ImageIcon(file.getName()));

I can see many answers, not really addressing the three questions of the OP.
1) A word on performance: byte arrays are likely unefficient unless you can use an exact pixel byte ordering which matches to your display adapters current resolution and color depth.
To achieve the best drawing performance, simply convert your image to a BufferedImage which is generated with a type corresponding to your current graphics configuration. See createCompatibleImage at https://docs.oracle.com/javase/tutorial/2d/images/drawonimage.html
These images will be automatically cached on the display card memory after drawing a few times without any programming effort (this is standard in Swing since Java 6), and therefore the actual drawing will take negligible amount of time - if you did not change the image.
Altering the image will come with an additional memory transfer between main memory and GPU memory - which is slow. Avoid "redrawing" the image into a BufferedImage therefore, avoid doing getPixel and setPixel at all means.
For example, if you are developing a game, instead of drawing all the game actors to a BufferedImage and then to a JPanel, it is a lot faster to load all actors as smaller BufferedImages, and draw them one by one in your JPanel code at their proper position - this way there is no additional data transfer between the main memory and GPU memory except of the initial transfer of the images for caching.
ImageIcon will use a BufferedImage under the hood - but basically allocating a BufferedImage with the proper graphics mode is the key, and there is no effort to do this right.
2) The usual way of doing this is to draw a BufferedImage in an overridden paintComponent method of the JPanel. Although Java supports a good amount of additional goodies such as buffer chains controlling VolatileImages cached in the GPU memory, there is no need to use any of these since Java 6 which does a reasonably good job without exposing all of these details of GPU acceleration.
Note that GPU acceleration may not work for certain operations, such as stretching translucent images.
3) Do not add. Just paint it as mentioned above:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this);
}
"Adding" makes sense if the image is part of the layout. If you need this as a background or foreground image filling the JPanel, just draw in paintComponent. If you prefer brewing a generic Swing component which can show your image, then it is the same story (you may use a JComponent and override its paintComponent method) - and then add this to your layout of GUI components.
4) How to convert the array to a Bufferedimage
Converting your byte arrays to PNG, then loading it is quite resource intensive. A better way is to convert your existing byte array to a BufferedImage.
For that: do not use for loops and copy pixels. That is very very slow. Instead:
learn the preferred byte structure of the BufferedImage (nowadays it is safe to assume RGB or RGBA, which is 4 bytes per pixel)
learn the scanline and scansize in use (e.g. you might have a 142 pixels wide image - but in the real life that will be stored as a 256 pixel wide byte array since it is faster to process that and mask the unused pixes by the GPU hardware)
then once you have an array build according to these principles, the setRGB array method of the BufferedImage can copy your array to the BufferedImage.

Setting JPanel background to transparent

I'm trying to build my own video player using VLCJ, but I have a problem.
My code is
import java.awt.*;
import javax.swing.*;
import com.sun.jna.*;
import uk.co.caprica.vlcj.component.*;
import uk.co.caprica.vlcj.runtime.*;
public class MainFrame extends JFrame {
public MainFrame(String vlcPath, String username) {
super("Player");
setSize(1366,700);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
NativeLibrary.addSearchPath(RuntimeUtil.getLibVlcLibraryName(), vlcPath);
EmbeddedMediaPlayerComponent player = new EmbeddedMediaPlayerComponent();
setContentPane(player);
JPanel panel = new JPanel();
player.add(panel, BorderLayout.EAST);
Dimension d = new Dimension(300,200);
panel.setOpaque(false);
panel.setLayout(null);
panel.setPreferredSize(d);
panel.setSize(d);
setVisible(true);
player.getMediaPlayer().playMedia("path to video");
}
}
Now, as you can see, I want the video player to be on the whole screen, and I want an overlay with transparent background on the right side.
This code gives me the following:
The background of the JPanel is for some reason black, not transparent. I tried creating my own class which extends JPanel and overrides paintComponent(Graphics g), but the result was the same.
The question is, how can I make it transparent?

The video is being played in a heavyweight AWT Canvas.
You can't overlay a transparent Swing component on top of that, it simply won't work.
Options:
Overlay a transparent top level Window and put your overlay in there - this works because your window manager can deal with transparency of a top-level window - the problem with this is it's a bit clunky because you have to keep both frames in sync if you move them or minimize them, also your window manager might implement some sort of blend effect which is not what you want;
Use the "direct" rendering media player and paint your own overlay on top of each frame - the downside is that it is less efficient than native rendering since your own application has to render each frame (it does work though);
Use only heavyweight components in your overlay, like Label - but even then the label itself will not have a transparent background;
For the approach described in #1, you can use the setOverlay() method on your EmbeddedMediaPlayer instance, also use enableOverlay() to turn the overlay on and off.
For the approach described in #2, well this is probably the cleanest approach since it does not rely on any clunky workarounds (like keeping two top-level windows in sync), at the cost of more CPU usage and non-native video playback.
None of this is ideal, but it's the best you can do.
You should also probably look in the vlcj test sources because there are examples showing how to do overlays like this.

JPanel: What is the simplest way to display an image?

I am working on a project and I need to display an image that I have already drawn. I need a background image and several foreground images that I can move around. What is the easiest way to do this? I haven't been able to find a clear answer.
ImageIcon image = new ImageIcon("imagename.jpg");
JLabel label = new JLabel("", image, JLabel.CENTER);
JPanel panel = new JPanel(new BorderLayout());
panel.add( label, BorderLayout.CENTER );
return panel;

The answer depends. Do you want to resize the background image to meet the requirements of the client are or not? If so, do you want to "fill" or "fit" the image to the area.
Take a look at Java: maintaining aspect ratio of JPanel background image for a lengthier discussion on the topic.
The next question you need to ask, is do you want to paint the animation on the surface or use existing components and move them instead...
You could check out...
Swing animation running extremely slow
https://stackoverflow.com/questions/15858623/how-to-use-a-swing-timer-to-animate/15859932#15859932
Drawing 2 Balls to move in different direction on Java but one disappeared
Java Bouncing Ball
Multiple bouncing balls thread issue
I am trying to make ball gradually move
the images are not loading
Which uses the paintComponent or direct paint method.
This approach is relatively common and easy to control. The problem is if you want to perform sub animation (ie animate the actually element separately from the main animation...think walking or spinning), then it becomes more difficult.
Check out
Java ball object doesn't bounce off of drawn rectangles like it's supposed to.
Which uses components instead. This method is good if you want to provide sub animation, but has the complexity of requiring you to size and position the components within the container.
Just as a side note. JLabel is a container ;)

The easiest way i've found is to create an entirely new class and extend JPanel like so:
import javax.swing.*;
import javax.imageio.*;
import java.io.*;
import java.awt.*;
public class Background extends JPanel {
private Image image;
public Background(){
this.setPreferredSize(new Dimension(width,height));
image =Toolkit.getDefaultToolkit().getImage("your_image.jpg");;
}
public void paintComponent(Graphics g) {
//paints the background image
super.paintComponent(g);
do{
}while(g.drawImage(image, 0, 0, null)==false);
}
}
To instantiate this class simply call this:
Background b= new Background();
From your main program.
Remember that b now acts as a Jpanel so you can simply call b.add(element)
If you don't understand what i've talked about and shown you, view this document on extending classes:
Extending Classes

drawing to a JPanel without inheritance

Right now I'm working on a program that throws up a bunch of separate (generated at runtime) images, each in their own window. To do this i've tried this approach:
public void display(){
JFrame window = new JFrame("NetPart");
JPanel canvas = new JPanel();
window.getContentPane().add(canvas);
Graphics g = canvas.getGraphics();
Dimension d = getSize();
System.out.println(d);
draw(g,new Point(d.minX*50,d.maxY*50), 50);
window.setSize(d.size(50));
window.setResizable(false);
window.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
window.setVisible(true);
}
public void draw(Graphics g, Point startLoc, int scale){
// generate and draw the image
}
public Dimension getSize(){
//returns my own dimensions class
}
However, this throws a NullPointerException in draw, claiming that the graphics is null. is there any way to externally draw to a JPanel from outside it (not inherit from JPanel and override PaintComponent)? Any help would be appreciated.

If you are drawing your images at runtime you should use BufferedImage.
Create a BufferedImage, call getGraphics() on it to get its Graphics object, draw to it using the Graphics(2D) api, then call Graphics.dispose() (not strictly necessary but a good habit) and as the previous poster suggested either create an ImageIcon with it and put in a JLabel using setIcon() or subclass JPanel / JComponent and draw it in paintComponent

You're finding out that getGraphics() won't work in this way since the Graphics object obtained is null prior to the component being rendered, and even when it is not null, it is not stable and becomes invalid with each redraw. Possible options include:
Creating ImageIcon from each Image, placing the icon in a JLabel and displaying the JLabel.
Biting the bullet and extending JPanel or other JComponent (you don't say why you're trying to avoid this) and displaying the image in the JPanel's paintComponent method.
Doing the above, but first creating a BufferedImage which is displayed in the paintComponent(...) method. Then you can modify the BufferedImage during the program's run if you need to change the display, add new images,...

a program that throws up a bunch of separate (generated at runtime) images,
each in their own window
don't do it that this way, don't create a lots of JFrames, these Object stays in the memory, until current JVM instance exists, result from this concept pretty could be OutOfMemory exceptions
don't create lots of JFrames, create only one JFrame, rest of Containers could be JDialog or JWindow
don't create a new JFrames, JDialogs or JWindows on the runtime, re_use the existing Containers
put these images as Icons to the JList or maybe better would be look at CardLayout

Pictures in a JPanel

I'm trying to write an application where I want to add different pictures on a Jpanel. Everything works fine except for the JPG format which displays very bad quality images.
This is how I do the drawing :
class draw extends Canvas
{
Dimension canvasSize = new Dimension(400, 400);
String fileName;
public void paint(Graphics g)
{
if(this.fileName!=null)
{
Toolkit toolkit = Toolkit.getDefaultToolkit();
Image img = toolkit.getImage(fileName);
g.drawImage(img, 0, 0, this);
}
}
public void setFileName(String name)
{
this.fileName=name;
}
public Dimension getMinimumSize()
{
return canvasSize;
}
public Dimension getPreferredSize()
{
return canvasSize;
}
}
Is there a way such that JPG format is covered ?

This is probably because you're stretching (or compressing) the image to the size of the canvas. JPEG images don't look great when you scale them, particularly if you're scaling up. Try an image that's the same size as (or close to) your canvas. You can also get the height and width of the JPEG from the Image class and display it in its original dimensions. Sun's Drawing an Image tutorial shows how to do this.

The posted code indicates that the OP is painting the image at its original size. So my comments about the code:
a) You say you want to add the image to a JPanel, yet for some reason you are extending Canvas. Stick with Swing components. Then if you need to do custom painting you would override the paintComponent() method NOT the paint method.
b) When you do use custom painting, you should never read the image in the painting method. This method can be called numerous times. It possible that the image has not been completely read into memory. I know Swing will automatically repaint as more of the image is read, I'm not sure how the AWT Canvas works.
c) Also, when overriding paint methods don't forget to invoke super.paint(), super.paintComponent() or you may get unexpected results.
d) However, based on the posted code there is no need to even do custom painting (since you are drawing the image at its actual size). Just create an ImageIcon from the image and add the Icon to a JLabel. Then you just add the label to the GUI.
I suggest you read the section from the Swing tutorial on How to Use Icons. If the image quality is poor then the problem is probably with your image because now you are using standard code, not custom code.