静态内部类和非静态内部类的区别

有两点区别

1. 静态内部类可以直接创建实例，而非静态必须要创建一个父类的实例之后才能创建子类的实例
2. 静态内部类只能访问父类的静态资源，而非静态可以访问所有资源

/* Java program to demonstrate how to implement static and non-static 
classes in a java program. */
class OuterClass{
    private static String msg = "GeeksForGeeks";

    // Static nested class 
    public static class NestedStaticClass{

        // Only static members of Outer class is directly accessible in nested 
        // static class 
        public void printMessage() {

            // Try making 'message' a non-static variable, there will be 
            // compiler error 
            System.out.println("Message from nested static class: " + msg);
        }
    }

    // non-static nested class - also called Inner class 
    public class InnerClass{

        // Both static and non-static members of Outer class are accessible in 
        // this Inner class 
        public void display(){
            System.out.println("Message from non-static nested class: "+ msg);
        }
    }
}
class Main
{
    // How to create instance of static and non static nested class? 
    public static void main(String args[]){

        // create instance of nested Static class 
        OuterClass.NestedStaticClass printer = new OuterClass.NestedStaticClass();

        // call non static method of nested static class 
        printer.printMessage();

        // In order to create instance of Inner class we need an Outer class 
        // instance. Let us create Outer class instance for creating 
        // non-static nested class 
        OuterClass outer = new OuterClass();
        OuterClass.InnerClass inner = outer.new InnerClass();

        // calling non-static method of Inner class 
        inner.display();

        // we can also combine above steps in one step to create instance of 
        // Inner class 
        OuterClass.InnerClass innerObject = new OuterClass().new InnerClass();

        // similarly we can now call Inner class method 
        innerObject.display();
    }
} 

参考：
https://www.geeksforgeeks.org/static-class-in-java/