Reflections on class and then declare their own instance of the class

class TreeNode {
    public int val;
    public TreeNode left;
    public TreeNode right;
}

This is similar to the original school is not fine ah! !

This is just a statement it did not create an instance

If you are a new class inside an instance and then instantiated in other places so the error will call this class

Exception in thread "main" java.lang.StackOverflowError

Here I felt struct structure inside like c ++

A closer Recall structure tmd Why did not studious = =

Structure where the write pointer and the structure pointer and array of structures of these concepts

And a structure inside the data structure pointer variable pointer field pondered what