Question

The purpose of this lab is to become familiar with searching, inserting and deleting elements in a linked list.using java  

public boolean contains(String name) // returns true if provided name exists in the list, otherwise returns false public void add(String name) // adds name to the list in its proper lexographical (alphabetical) ordering public void delete(String name) // removes name from list

Answer 1

    public boolean contains(String name) {
                Node temp = this.head;
                while (temp != null) {
                        if (temp.data.compareTo(name) == 0) {
                                return true;
                        }
                        temp = temp.next;
                }
                return false;
        }

        public void add(String name) {
                // if list is empty add directly
                if (this.head == null) {
                        Node nn = new Node();
                        this.head = nn;
                }
                // else insert in alphabetical order
                else {
                        // dummy node used for searching position where the node should be inserted
                        Node dummy = new Node();
                        Node current = dummy;
                        dummy.next = this.head;

                        // iterate until correct position is found
                        while (current.next != null && current.next.data.compareTo(name) < 0) {
                                current = current.next;
                        }

                        // insert node
                        Node nn = new Node();
                        nn.next = current.next;
                        current.next = nn;
                }
        }

        public void delete(String name) {
                Node temp = this.head;
                while (temp != null) {
                        if (temp.data.compareTo(name) == 0) {
                                // search for prev node
                                Node prev = prev(name);
                                // remove the current node
                                prev.next = temp.next;
                        }
                        temp = temp.next;
                }
        }

        private Node prev(String name) {
                Node temp = this.head;
                while (temp != null) {
                        if (temp.next.data.compareTo(name) == 0) {
                                return temp;
                        }
                        temp = temp.next;
                }
                return null;
        }

Since the linkedlist structure was not specified clearly , standard definition is used to complete the code.Feel free to comment in case of any doubts.