question: isvalidnode returns true if this node is valid ; false otherwise . by default , an invalid node is one that does n't belong to a list mylist is null , but subclasses can override this definition . concode_field_sep Object item concode_elem_sep List myList concode_field_sep ListNode next concode_elem_sep Object item concode_elem_sep ListNode prev concode_elem_sep void setItem concode_elem_sep void insertAfter concode_elem_sep void remove concode_elem_sep void insertBefore
target: boolean function ( ) { return myList != null ; }