A truly ugly utility method
The worst way to write the convertOzToMl() method (the way that yields the maximum coupling) is to take an input from a public static variable and put the output in another public static variable. A public static (but not final) variable in Java is equivalent in functionality and danger to global variables of C or C++. Here's an example:

// In source packet in file coupling/ex4/Liquid.java
// THIS APPROACH WORKS, BUT MAKES THE CODE HARD TO UNDERSTAND
// AND HARD TO CHANGE
class Liquid {

    private static final double FL_OUNCES_PER_ML = 12.0/355.0;
    private static final double ML_PER_FL_OUNCE = 355.0/12.0;

    /**
    * Converts fluid ounces to milliliters
    */
    public static void convertOzToMl() {

        double d = PurpleZebra.k * ML_PER_FL_OUNCE;
        d += 0.5;
        FlyingSaucer.q = (int) d;
    }
}

// In source packet in file coupling/ex4/FlyingSaucer.java
class FlyingSaucer {
	public static int q;
	//...
}

// In source packet in file coupling/ex4/PurpleZebra.java
class PurpleZebra {
    public static int k;
    //...
}

To use the above version of convertOzToMl(), a programmer would have to do the following:

// In source packet in file coupling/ex4/Example4.java
class Example4 {

    public static void main(String[] args) {

        PurpleZebra.k = 16;
        Liquid.convertOzToMl();
        int mlFor16Oz = FlyingSaucer.q;

        System.out.println("Ml for 16 oz is: " + mlFor16Oz);
    }
}