equals() you should also
override hashCode().
The hashCode() method should ideally return
the same int for any two objects that compace equal
and a different int for any two objects that
don't compare equal, where equality is defined by
the equals() method. This is used as
an index by the java.util.Hashtable class.
In the Car example equality is determined exclusively
by comparing license plates; therefore
only the licesePlate field is used to determine the hash code.
Since licensePlate is a String, and since the String class has its own hashCode() method,
we can sponge off of that.
public int hashCode() {
return this.licensePlate.hashCode();
}
java.lang.Double, java.lang.Float, etc.)
that convert primitive data types to integers that
share the same bit string.
These can be used to hash primitive data types.