Behind the scenes, color isn’t really a type. Processing automatically converts color values into int values. That’s why the color type doesn’t work with Java code: Java doesn’t know about this color to int magic.
To get your example working, you can use Integer values instead:
import java.util.*;
Integer[] array;
List<Integer> l;
void setup() {
size(600,600);
array = new Integer[]{#FEF0D5, #D81E5B, #F35B68, #00BEB2, #1A5D63};
// Shuffle the elements in the array
l = Arrays.asList(array);
printArray("original order: " + l);
}
void draw() {
color c = array[0];
background(c);
}
void keyPressed() {
Collections.shuffle(l);
printArray("new order: " + l);
}
Also notice the code inside the draw() function which treats the Integer value like a color. Processing knows that color values are really int values, so this will work.
By the way, the Color type (with an upper-case C) is a Java-specific class that you should (almost) never use in Processing.