Method equals

src/main/java/ev3dev/sensors/EV3Key.java:262–271

@param obj @return true if the obj is an instance of Key and if the button IDs are the same.

(final Object obj)

     * @return true if the {@code obj} is an instance of {@link Key} and if the button IDs are the same.
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj == null || ! (obj instanceof Key)) {
            return false;
        } else if (obj == this) {  // pointer comparison
            return true;
        } else {
            return ((int)this.keyType.getId() == ((Key)obj).getId());
        }
    }

    /**
     * @return the button ID based hash code