内部类轻量级？ [英] Are Inner Classes lightweight?

问题描述

内部类比普通类更轻量，或者在最后java编译内部类就像正常类？

我知道java中的类不是非常轻量级自己，他们占用了部分permgen内存，所以我想知道如果最好使用闭包类函数作为内部类，或者如果标准类也会很好吗？

.class 文件。例如：

  class Outer {
 class Inner {
 
} 
 
对象函数（）{
 return new Object（）{
 
}; 
} 
} 
  

将生成三个 .class 文件， Outer.class ，外部$ Inner.class 和 Outer $ 1.class 。他们不是比其他类更轻量级，并且（据我所知），从性能角度来看，使用一个没有优势。当然，内部类，特别是匿名内部类在上下文中非常有用，在这种情况下，常规类更难于编码，但这是一个单独的问题。

Are inner classes more lightweight than normal classes, or in the end java compiles inner classes just like normal classes?

I know classes in java are not all very lightweight themselves, and they occupy part of the permgen memory, so I'd like to know if it's best to use closure-like functions as inner classes, or if standard classes would also do fine?

解决方案

Inner classes and anonymous inner classes both compile down to .class files. For example:

class Outer {
     class Inner {

     }

     Object function() {
          return new Object() {

          };
     }
}

Will generate three .class files, Outer.class, Outer$Inner.class, and Outer$1.class. They aren't more "lightweight" than other classes, and (to the best of my knowledge) there's no advantage to using one over the other from a performance perspective. Of course, inner classes and especially anonymous inner classes are really useful in contexts where regular classes are harder to code, but that's a separate issue.

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