Static and Nested Classes ???

[Cecil Phillip]

Why do I get an error on Graph and not on Graph3 when i compile this ?

public class MST2 {
    
    class Graph {
        
        static class Edge { 
        }
        
        static class Vertex {            
        }
    }
 
    static class Graph2{  }
    
    static class Graph3 {
        static class nested{
        }
    }
}

[Keith Lynn]

An inner class cannot contain static members unless they are compile-time constants.