静态内部类的加载方式

非内部类的静态成员变量会直接加载

public class OuterClass
{
    static{
        System.out.println("OuterClass static load.");
    }  

    public OuterClass()
    {
        System.out.println("flag");
    }
    public OuterClass(String flag)
    {
        System.out.println("flag:"+flag);
    }  

    class InnerClass
    {
        //private static String te = "";
        /*static{
            System.out.println("InnerClass static load.");
        }*/
        private OuterClass out = new OuterClass("inner");
    }
    static class InnerStaticClass
    {
        private static OuterClass out = new OuterClass("innerStatic");
        static{
            System.out.println("InnerStaticClass static load.");
        }
        private static void load()
        {
            System.out.println("InnerStaticClass func load().");
        }
    }
    public static  OuterClass getInstatnce()
   {
      return OuterClass.InnerStaticClass.out;
   }
    public static void main(String[] args)
    {
//        OuterClass.InnerStaticClass.load();
//        OuterClass out = OuterClass.InnerStaticClass.out;
//        OuterClass.InnerClass innerClass = out.new InnerClass() ;
        //OuterClass.InnerStaticClass.out.
    }  

} 

打印结果：OuterClass static load.

public class OuterClass
{
    static{
        System.out.println("OuterClass static load.");
    }  

    public OuterClass()
    {
        System.out.println("flag");
    }
    public OuterClass(String flag)
    {
        System.out.println("flag:"+flag);
    }  

    class InnerClass
    {
        //private static String te = "";
        /*static{
            System.out.println("InnerClass static load.");
        }*/
        private OuterClass out = new OuterClass("inner");
    }
    static class InnerStaticClass
    {
        private static OuterClass out = new OuterClass("innerStatic");
        static{
            System.out.println("InnerStaticClass static load.");
        }
        private static void load()
        {
            System.out.println("InnerStaticClass func load().");
        }
    }
    public static  OuterClass getInstatnce()
   {
      return OuterClass.InnerStaticClass.out;
   }
    public static void main(String[] args)
    {
        OuterClass.InnerStaticClass.load();
//        OuterClass out = OuterClass.InnerStaticClass.out;
//        OuterClass.InnerClass innerClass = out.new InnerClass() ;
        //OuterClass.InnerStaticClass.out.
    }  

}  

内部类只会在第一次使用时加载，不使用就不加载。打印结果：

OuterClass static load.
flag:innerStatic
InnerStaticClass static load.
InnerStaticClass func load().

public class OuterClass
{
    static{
        System.out.println("OuterClass static load.");
    }  

    public OuterClass()
    {
        System.out.println("flag");
    }
    public OuterClass(String flag)
    {
        System.out.println("flag:"+flag);
    }  

    class InnerClass
    {
        //private static String te = "";
        /*static{
            System.out.println("InnerClass static load.");
        }*/
        private OuterClass out = new OuterClass("inner");
    }
    static class InnerStaticClass
    {
        private static OuterClass out = new OuterClass("innerStatic");
        static{
            System.out.println("InnerStaticClass static load.");
        }
        private static void load()
        {
            System.out.println("InnerStaticClass func load().");
        }
    }
    public static  OuterClass getInstatnce()
   {
      return OuterClass.InnerStaticClass.out;
   }
    public static void main(String[] args)
    {
        OuterClass.InnerStaticClass.load();
        OuterClass out = OuterClass.InnerStaticClass.out;
        OuterClass.InnerClass innerClass = out.new InnerClass() ;
    }  

}  打印结果：

OuterClass static load.
flag:innerStatic
InnerStaticClass static load.
InnerStaticClass func load().
flag:inner