Java Reference
In-Depth Information
id created
[instance] id.double2 = 1.0
[instance] id.double4 = 10.0
[instance] id.int2 = 1000000000
[instance] id.string2 = abc
initializers and instance initializers, you will discover some interesting facts about ini-
• Classfieldsinitializetodefaultorexplicitvaluesjustafteraclassisloaded.Im-
within the <clinit>() method performs explicit initialization.
• All class initialization occurs prior to the <clinit>() method returning.
• Instance fields initialize to default or explicit values during object creation.
When new allocatesmemoryforanobject,itzeroesallinstancefieldstodefault
values. Code within an <init>() method performs explicit initialization.
• All instance initialization occurs prior to the <init>() method returning.
tents of an instance field before that field is declared causes the compiler to report an
illegal forward reference .
Inheriting State and Behaviors
are bank accounts.” By making these statements, we really are saying that cars inherit
vehicular state (e.g., make and color) and behaviors (e.g., park and display mileage),
real-worldentitycategories,and inheritance isahierarchicalrelationshipbetweensim-
otherentitycategory.Inheritingfromasinglecategoryiscalled single inheritance ,and
inheriting from at least two categories is called multiple inheritance .
Java supports single inheritance and multiple inheritance to facilitate code re-
use—why reinvent the wheel? Java supports single inheritance in a class context, in
which a class inherits state and behaviors from another class through class extension.
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