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Can I assign an image gradient to a rectangle

I'm currently making Mario as a school graphics project.
I have most of the collisions done, but I just want the land and bricks to actually look like land and bricks instead of just colored rectangles. I have an ImageIcon for the "land" in my graphics project. The problem is that it is only 16x16 pixels large. In order to make enough land by just making each part of the land one 16x16 pixel, it would essentially be horribly inefficient.
I was wondering if I could get the ImageIcon or possibly buffered image and use it as the "color" for a rectangle to make the chunks of land easier. If that's not possible, can you offer other suggestions on how to go about this problem?

Using a background of tiled images, a texture:
private BufferedImage image;
URL url = getClass().getResource("/mytexture.png");
assert url != null;
image = ImageIO.read(url);
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
Rectangle rect = new Rectangle(0, 0, width, height);
Rectangle textureRect = new Rectangle(0, 0, image.getWidth(), image.getHeight());
TexturePaint paint = new TexturePaint(image, textureRect);
g2.setPaint(paint);
g2.fill(rect);
}
In general create your own JPanel.
Gimp and other tools allow to create a tilable image by ensuring that a line running to a border will enter at the opposite border.

Java Graphics2D Image Moving

So in this block of code, a 40x40 square can move across a window by calling directional methods, and I'm trying to get a spaceship to appear instead of the square. No matter what I try, it just isn't working.
public void paintComponent (Graphics g) {
ImageIcon wallpaper = new ImageIcon("images/JGalagawallpaper.png");
image = wallpaper.getImage();
g.drawImage(image, 400, 400, null);
ImageIcon ship = new ImageIcon("images/galaga.png");
galaga = ship.getImage();
super.paintComponent(g);
Graphics2D graphic = (Graphics2D) g;
graphic.fill(new Rectangle.Double(x, y, 40, 40));
//graphic.drawImage(galaga, x, y, 40, 40);
}
My question is, how do I get that thing to appear? I already tried tinkering with graphic.drawImage, however that didn't really work out as well as I hoped. That's what the commented out code is.

g.drawImage(image, 400, 400, null);
First you draw the image.
super.paintComponent(g);
Then you invoke the above code which is used to pint the background color of the panel, thus overwriting the image. The above statement should be the first statement of the painting method.
ImageIcon wallpaper = new ImageIcon("images/JGalagawallpaper.png");
A painting method is for painting only. Don't do I/O in the method. The image should be read in the constructor of your class so that it is only read once, not every time the component is repainted.
You also need to look at the coordinates of where you paint the image. Maybe the panel is not that big?
Did you verify that the image was read properly by display its size?

Black image when drawing Image on Canvas

I am working on a game in which I am use Canvas to display my graphics. I haven't (and don't plan on) using any Swing components...
In my render method:
I am using a BufferStrategy that I get from the canvas.
BufferStrategy bs = this.getBufferStrategy();
if(bs == null){
createBufferStrategy(3);
return;
}
Graphics g = bs.getDrawGraphics();
Later in the same method I end up drawing images(entities, trees, map, etc.), disposing of g, and showing the reference 'bs'.
...drawings onto canvas(entities, trees, map, etc.)
//END RENDER
g.dispose();
bs.show();
In between when I //END RENDER and finish drawing to g I ask if the game is paused. If so I am create a BufferedImage from what was made by g. I render that BufferedImage and then render my inventory screen on top of that:
BufferedImage img = new BufferedImage(this.width, this.height, BufferedImage.TYPE_3BYTE_BGR);
Graphics gx = img.getGraphics();
game.paint(gx);
g.drawImage(img, 0, 0, Color.CYAN, this);
interfaceLayer.render(g);
I am getting a black BufferedImage in my reference img.
Am I doing something wrong by using a BufferStrategy? Should I not be using two different Graphics objects?
Here is a picture of what it looks like before and after I pause the game to get an idea.
Instead of:
g.drawImage(img, 0, 0, Color.CYAN, this);
I changed it to:
g.drawImage(img, 20, 20, Color.CYAN, this);
Just some arbitrary x,y so you can get the idea of whats going on with they layering.
Dont mind the gray box. It is a fillRect() that I will eventually be expanding as part of the graphics in my inventory screen.
Why the black image?

Save a drawn picture on a JPanel in a file [java]

I've made a code to draw on a Jpanel
frame1.add( new JPanel() {
public void paintComponent( Graphics g ) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setColor(Color.white);
g2.fillRect(0, 0, width, height);
//Drawnig Part
});
Every thing is OK
Now My question is how to save what I've drawn on my JPanel in a file a.PNG or any other type
I have spent a lot of time to write the Drawing Part, So it will be helpful if you can suggest a solution by changing the required parts of my code, instead of rewriting the whole code.

I suggest that you buffer your drawing operations with a BufferedImage, like so:
// This should not be done in the draw method, but rather when
// the frame is created. You should also make a new buffer image when
// the frame is resized. `frameWidth` and `frameHeight` are the
// frame's dimensions.
BufferedImage bufferImage = new BufferedImage(frameWidth, frameHeight,
BufferedImage.TYPE_INT_ARGB);
Graphics2D bufferGraphics = bufferImage.createGraphics();
// In your draw method, do the following steps:
// 1. Clear the buffer:
bufferGraphics.clearRect(0, 0, width, height);
// 2. Draw things to bufferGraphics...
// 3. Copy the buffer:
g2.drawImage(bufferImage, null, 0, 0);
// When you want to save your image presented in the frame, call the following:
ImageIO.write(bufferImage, "png", new File("frameImage.png"));
The Java Tutorial on Creating and Drawing to an Image, along with the ImageIO API reference might be helpful should you require more information.

Have a look at Writing/Saving an Image for more details, but essentially you can do something like...
BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
// Draw what ever you want to to the graphics context
g2d.dispose();
ImageIO.write(img, "png", new File("My Awesome Drawing.png"));
If you can't separate the drawing logic from your panel, you could simply use the Graphics context from the BufferedImage to paint the the component with.
Have a look at Exporting a JPanel to an image and Print the whole program layout for examples

Creating and rendering an image dynamically with transparent background for use with drawImage

Could someone provide an example of how to dynamically create an image in Java, draw lines et cetera on it, and then draw the image so that areas not painted will remain transparent in the drawing process?

One could use a BufferedImage with an image type that supports transparency such as BufferedImage.TYPE_INT_ARGB:
BufferedImage img = new BufferedImage(100, 100, BufferedImage.TYPE_INT_ARGB);
One can draw on the BufferedImage by calling BufferedImage.createGraphics to obtain a Graphics2D object, then perform some drawing:
BufferedImage img = new BufferedImage(100, 100, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = img.createGraphics();
g.drawLine(0, 0, 10, 10); // draw a line.
g.dispose();
Then, since BufferedImage is a subclass of Image that can be used to draw onto another Image using one of the Graphics.drawImage that accepts an Image.