is it incorrect to define an hashcode of an object as the sum, multiplication, whatever, of all class variables hashcodes?

Let's say I have the following class:

class ABC {
    private int myInt = 1;
    private double myDouble = 2;
    private String myString = "123";
    private SomeRandomClass1 myRandomClass1 = new ...
    private SomeRandomClass2 myRandomClass2 = new ...

    //pseudo code
    public int myHashCode() {
        return 37 *
               myInt.hashcode() *
               myDouble.hashCode() *
               ... *
               myRandomClass.hashcode()
    }
}

Would this be a correct implementation of hashCode? This is not how I usually do it(I tend to follow Effective Java's guide-lines) but I always have the temptation to just do something like the above code.

Thanks