if the head is empty , then the list is empty . this method returns true if the list is empty . if the list is not empty , it returns false . concode_field_sep Node head concode_elem_sep int size concode_field_sep void printSortedList concode_elem_sep void printBinaryTree concode_elem_sep int getSize concode_elem_sep void printCompression concode_elem_sep void insertionSort concode_elem_sep void insertionSort concode_elem_sep void compress concode_elem_sep Node getHead concode_elem_sep void createTree concode_elem_sep void preorderTraversal concode_elem_sep void setHead
boolean function ( ) { return ( head == null ) ; }