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  • Nested Class

    1. Why Use Nested Classes?

    There are several compelling reasons for using nested classes, among them:

    • It is a way of logically grouping classes that are only used in one place.
    • It increases encapsulation.
    • Nested classes can lead to more readable and maintainable code.

    2. Taxonomy of Classes

    2.1 Static Nested Classes

    A static nested class is associated with its outer class. And like static class methods, a static nested class cannot refer directly to instance variables or methods defined in its enclosing class — it can use them only through an object reference.

    2.1.1 Create an object for the static nested class

    OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass();
    2.1.2 When to use static nested class
    B is A's assistant class and only be used by A, define B as A's static nested class like JDK's LinkedList and it's Entry.
     

    2.2 Inner Classes

    As with instance methods and variables, an inner class is associated with an instance of its enclosing class and has direct access to that object's methods and fields. Also, because an inner class is associated with an instance, it cannot define any static members itself.

    2.2.1 Instantiate an inner class

    OuterClass.InnerClass innerObject = outerObject.new InnerClass();
    2.2.2 Obtain outer class's reference
    OuterClass.this
    2.2.3 When to use
    Inner class's most important feature is it can access outer class's any fields or methods, for example, in JDK's Collection
    library, every collection must provide a according Iterator to support unified collection traversal.
     
    2.3 Anonymous Inner Classes
     An inner class within the body of a method without naming it

    2.3.1 When to use

    The class has few code to implement

    Taxonomy of Classes in Java Programming

    版权声明:本文为博主原创文章,未经博主允许不得转载。

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  • 原文地址:https://www.cnblogs.com/significantfrank/p/4875855.html
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