Java™ How To Program (Early Objects), Tenth Edition

21.4.7 List Method removeFromFront

Method removeFromFront (lines 78–92 of Fig. 21.3) removes the first node of the list and returns a reference to the removed data. If the list is empty when the program calls this method, the method throws an EmptyListException (lines 80–81). Otherwise, the method returns a reference to the removed data. The steps are:

1. Assign firstNode.data (the data being removed) to removedItem (line 83).

2. If firstNode and lastNode refer to the same object (line 86), the list has only one element at this time. So, the method sets firstNode and lastNode to null (line 87) to remove the node from the list (leaving the list empty).

3. If the list has more than one node, then the method leaves reference lastNode as is and ...