内部类的四种实现方式

内部类分为四种：

1.成员内部类
2.局部内部类
3.静态内部类
4.匿名内部类

1.成员内部类

Java code

   

    <!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
     
    //
    成员内部类......相当于非静态方法
     
    class
     MemberInner { 
    private
     
    int
     a 
    =
     
    3
    ; 
    public
     
    class
     Inner2 { 
    private
     
    int
     a 
    =
     
    2
    ; 
    public
     
    void
     doSomething() { 
    //
     调用外部类的属性
     
     System.out.println(MemberInner.
    this
    .a);
    //
     这块要注意......很重要！！！
     
     System.out.println(a); } } } 
    public
     
    class
     Test3 { 
    public
     
    static
     
    void
     main(String[] args) { MemberInner.Inner2 inner2 
    =
     
    new
     MemberInner().
    new
     Inner2();
    //
     非静态内部类要new实例
     
     inner2.doSomething(); } } 

   

2.静态内部类

Java code

   

    <!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
     
    //
    静态内部类......相当于静态方法
     
    class
     StaticInner{ 
    private
     
    static
     
    int
     a
    =
    3
    ; 
    public
     
    static
     
    class
     Inner{ 
    public
     
    void
     test(){ System.out.println(a); } } } 
    public
     
    class
     Test2 { 
    public
     
    static
     
    void
     main(String[] args) { StaticInner.Inner inner
    =
    new
     StaticInner.Inner();
    //
    静态内部类直接调用
     
     inner.test(); } } 

   

3.局部内部类

Java code

   

    <!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
     
    //
    局部内部类......相当于局部变量
     
    class
     LocalInner { 
    public
     
    void
     doSomething(
    int
     b) { 
    final
     
    int
     a 
    =
     
    3
    ;
    //
     只能访问final的变量
     
     
    class
     Inner3 { 
    public
     
    void
     test(
    int
     b) { System.out.println(b); System.out.println(a); } } 
    new
     Inner3().test(b); } } 
    public
     
    class
     Test4 { 
    public
     
    static
     
    void
     main(String[] args) { LocalInner inner 
    =
     
    new
     LocalInner(); inner.doSomething(
    4
    ); } }