USING COLORS WITH THE STANDARD GRAPHICS LIBRARY

The Java class Color allows you to use a myriad of built-in colors. Or, you can create your own from RGB or HSB formats. (We'll introduce classes in Section 3.1.) To access the Color class, you need to include the following statement at the beginning of your Java program:

import java.awt.Color

You can now set the foreground color to blue using our standard graphics library with:

StdDraw.setColor(Color.blue);

or clear the background with

StdDraw.clear(Color.lightGray);

The default foreground color is black and the default background color is white.

Built-in colors. The following colors are built-in:

Color.black
Color.blue
Color.cyan
Color.darkGray
Color.gray
Color.green
Color.lightGray
Color.magenta
Color.orange
Color.pink
Color.red
Color.white
Color.yellow

User-defined colors. There are a number of ways to construct your own colors. For complete details check out the Java Color API. Unless you have extreme needs, the following examples will probably suffice:

RGB format. RGB format specifies a color by three integer values between 0 and 255, representing the combination of red, green, and blue in the color. This format is commonly used in television screens, computer monitors, digital cameras, and web pages. (The primary color green is used instead of yellow because yellow phosphors are much more expensive to produce.) You can create your own colors as follows:
```
StdDraw.setColorRGB(255,   0,   0);   // red
StdDraw.setColorRGB(  0, 255,   0);   // green
StdDraw.setColorRGB(  0,   0, 255);   // blue
StdDraw.setColorRGB(255, 255,   0);   // yellow
StdDraw.setColorRGB(255, 255, 255);   // white
StdDraw.setColorRGB(  0,   0,   0);   // black
StdDraw.setColorRGB(100, 100, 100);   // gray
```
Note that if all three parameters are the same, you get a shade of gray. Web pages typically specify the colors in RGB format, but as a 24-bit hexadecimal integer. You can achieve the same effect in Java.
```
StdDraw.setColor(Color.decode("#00ffff"));    // cyan
```
HSB format. HSB format specifies a color by three integer values between 0 and 255, representing the hue, saturation, and brightness. The hue determines the color (from red to orange, yellow, green, blue, indigo, and violet). The brightness determines the intensity (from light or dark). The saturation determines the color depth (from dull to intense). This format roughly corresponding to the way in which the human eye perceives color. You can achieve a nice rainbow effect by varying the hue, while holding the saturation and brightness at 255. This can be useful for visualizing scientific data. For example, if you are plotting the movement of a particle over time, you might plot the particle in a different color at each time step.
```
for (int i = 0; i <256; i++) { stddraw.setcolorhsb(i, 255, 255); // plot something } 
```
It's also can be fun to generate random colors. The following code fragment generates a random color from the rainbow.
```
int r = (int) (Math.random() * 256);
StdDraw.setColorHSB(r, 255, 255);
```