Adding a first attempt at all the methods required in this homework.

fourthassignment/src/main/java/com/ds/fourthassignment/CircularLinkedList.java

@@ -42,11 +42,28 @@ public class CircularLinkedList {
 		size++;
 	}
 	
+	/**
+	 * middle is neither at the beginning nor at the end
+	 * 
+	 * @param newNode the node to be added to the middle of the list
+	 */
+	public void addToMiddle(LNode newNode) {
+		int curPos = 0;
+		LNode curNode = head;
+		if(this.size > 2){
+			while(curPos < this.size/2){
+				curPos ++;
+				curNode = curNode.getNext();
+			}
+		}
+		newNode.setNext(curNode.getNext());
+		curNode.setNext(newNode);
+	}
 	
 	public String display(){
 		String out=""; 
 		if (head==null) return null;
-		LNode current = head; 
+		LNode current = head;
 		do{
 			out+=current.getData() +",";
 			if (current==tail) break;

fourthassignment/src/main/java/com/ds/fourthassignment/DoublyLNode.java

 package com.ds.fourthassignment;
 
+/**
+ * This now supports the scientist type
+ */
+
 public class DoublyLNode {
 
-	private String data; 
+	private Scientist data; 
 	private DoublyLNode next;
 	private DoublyLNode previous; 
 	
-	public DoublyLNode (String data, DoublyLNode previous , DoublyLNode next){
+	public DoublyLNode (Scientist data, DoublyLNode previous , DoublyLNode next){
 		this.data = data;
 		this.next = next;
 		this.previous = previous; 
@@ -24,7 +28,7 @@ public class DoublyLNode {
 	
 	public boolean hasPrevious() { return (previous==null ? false : true); }
 	
-	public String getData() { return data;}
+	public Scientist getData() { return data;}
 	public DoublyLNode getNext() {return next; }
 	public DoublyLNode getPrevious() { return previous; }
 	

fourthassignment/src/main/java/com/ds/fourthassignment/DoublyLinkedList.java

@@ -82,4 +82,26 @@ public class DoublyLinkedList {
 		return out;
 	}
 	
+	/**
+	 * TODO
+	 * Implement the method indexOfElement(Scientist s) to return the
+	 * index of an input element (based on the name of a scientist). Suppose
+	 * the elements are unique. Add this method to class DoubleLinkedList
+	 * 
+	 * @return the index of this scientist, or -1
+	 */
+	public int indexOfElement(Scientist s){
+		DoublyLNode curNode = head;
+		int curIndex = 0;
+		do{
+			if(curNode.getData().compareTo(s) == 0){
+				return curIndex;
+			}
+			curNode = curNode.getNext();
+			curIndex ++;
+		} while(curNode.hasNext());
+		return -1;
+	}
+
+	
 }
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fourthassignment/src/main/java/com/ds/fourthassignment/TLinkedList.java

@@ -39,7 +39,12 @@ public class TLinkedList {
 		
 	}
 	
-	
+	/**
+	 * TODO: check if addSorted works for:
+	 * 
+	 * Create an add method that keeps nodes sorted in
+descending order.
+	 */
 	
 	/**
 	 *This method adds nodes to the list and keeps the list sorted.
@@ -85,7 +90,6 @@ public class TLinkedList {
 		}
 		previous.setNext(node);
 		size++;
-		
 	}
 	
 	/**
@@ -122,4 +126,16 @@ public class TLinkedList {
 	 */
 	public int getSize(){ return size; }
 
+	/**
+	 * Search method to perform linear search based on the
+	 * name field of a scientist object. If the query is found, remove and
+	 * return the matched Scientist object
+	 * 
+	 * @param needle The scientist your searching for
+	 * @return The found Scientist or null if no scientist was found
+	 */
+	public Scientist search(Scientist needle){
+		return null;
+	}
+
 }
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