三生石@ 2008-09-16 08:22 采纳率: 100%
浏览 1196
已采纳

Java 内部类和静态嵌套类

What is the main difference between an inner class and a static nested class in Java? Does design / implementation play a role in choosing one of these?

转载于:https://stackoverflow.com/questions/70324/java-inner-class-and-static-nested-class

  • 写回答

24条回答 默认 最新

  • 撒拉嘿哟木头 2008-09-16 08:28
    关注

    From the Java Tutorial:

    Nested classes are divided into two categories: static and non-static. Nested classes that are declared static are simply called static nested classes. Non-static nested classes are called inner classes.

    Static nested classes are accessed using the enclosing class name:

    OuterClass.StaticNestedClass
    

    For example, to create an object for the static nested class, use this syntax:

    OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass();
    

    Objects that are instances of an inner class exist within an instance of the outer class. Consider the following classes:

    class OuterClass {
        ...
        class InnerClass {
            ...
        }
    }
    

    An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance.

    To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax:

    OuterClass.InnerClass innerObject = outerObject.new InnerClass();
    

    see: Java Tutorial - Nested Classes

    For completeness note that there is also such a thing as an inner class without an enclosing instance:

    class A {
      int t() { return 1; }
      static A a =  new A() { int t() { return 2; } };
    }
    

    Here, new A() { ... } is an inner class defined in a static context and does not have an enclosing instance.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(23条)

报告相同问题?

悬赏问题

  • ¥15 求差集那个函数有问题,有无佬可以解决
  • ¥15 【提问】基于Invest的水源涵养
  • ¥20 微信网友居然可以通过vx号找到我绑的手机号
  • ¥15 寻一个支付宝扫码远程授权登录的软件助手app
  • ¥15 解riccati方程组
  • ¥15 display:none;样式在嵌套结构中的已设置了display样式的元素上不起作用?
  • ¥15 使用rabbitMQ 消息队列作为url源进行多线程爬取时,总有几个url没有处理的问题。
  • ¥15 Ubuntu在安装序列比对软件STAR时出现报错如何解决
  • ¥50 树莓派安卓APK系统签名
  • ¥65 汇编语言除法溢出问题