Objective Manipulate the Linked List Pointer.Make acopy of LList..pdf
- 1. Objective: Manipulate the Linked List Pointer. Make acopy of LList.java and rename it to LListr.java. Add a reverse function in LListr.java to reverse the order of the linked list. You can either use the gamescore.txt to test the reverse function. Llist.Java File: /** Source code example for "A Practical Introduction to Data Structures and Algorithm Analysis, 3rd Edition (Java)" by Clifford A. Shaffer Copyright 2008-2011 by Clifford A. Shaffer */ // Doubly linked list implementation class LList implements List { private DLink head; // Pointer to list header private DLink tail; // Pointer to last element in list protected DLink curr; // Pointer ahead of current element int cnt; // Size of list //Constructors LList(int size) { this(); } // Ignore size LList() { curr = head = new DLink(null, null); // Create header node tail = new DLink(head, null); head.setNext(tail); cnt = 0; } public void clear() { // Remove all elements from list head.setNext(null); // Drop access to rest of links curr = head = new DLink(null, null); // Create header node tail = new DLink(head, null); head.setNext(tail); cnt = 0; } public void moveToStart() // Set curr at list start { curr = head; } public void moveToEnd() // Set curr at list end { curr = tail.prev(); }
- 2. /** Insert "it" at current position */ public void insert(E it) { curr.setNext(new DLink(it, curr, curr.next())); curr.next().next().setPrev(curr.next()); cnt++; } /** Append "it" to list */ public void append(E it) { tail.setPrev(new DLink(it, tail.prev(), tail)); tail.prev().prev().setNext(tail.prev()); cnt++; } /** Remove and return current element */ public E remove() { if (curr.next() == tail) return null; // Nothing to remove E it = curr.next().element(); // Remember value curr.next().next().setPrev(curr); curr.setNext(curr.next().next()); // Remove from list cnt--; // Decrement the count return it; // Return value removed } /** Move curr one step left; no change if at front */ public void prev() { if (curr != head) // Can't back up from list head curr = curr.prev(); } // Move curr one step right; no change if at end public void next() { if (curr != tail.prev()) curr = curr.next(); } public int length() { return cnt; } // Return the position of the current element public int currPos() { DLink temp = head; int i; for (i=0; curr != temp; i++) temp = temp.next();
- 3. return i; } // Move down list to "pos" position public void moveToPos(int pos) { assert (pos>=0) && (pos<=cnt) : "Position out of range"; curr = head; for(int i=0; i. The vertical * bar represents the current location of the fence. This method * uses toString() on the individual elements. * @return The string representation of this list */ public String toString() { // Save the current position of the list int oldPos = currPos(); int length = length(); StringBuffer out = new StringBuffer((length() + 1) * 4); moveToStart(); out.append("< "); for (int i = 0; i < oldPos; i++) { if (getValue()!=null) { out.append(getValue()); out.append(" "); } next(); } out.append("| "); for (int i = oldPos; i < length; i++) { out.append(getValue()); out.append(" "); next(); } out.append(">"); moveToPos(oldPos); // Reset the fence to its original position return out.toString();
- 4. } } gamescore.txt Mike,1105 Rob,750 Paul,720 Anna,660 Rose,590 Jack,510 gamescore.txt Solution Here is the function you need: public void reverseList() { DLink oldStart = tail; //Copies the last node address. DLink temp; //Holds a temporary pointer to hold a node. moveToStart(); //Makes the current move to the first position. while(oldStart != head) { temp = remove(); //Removes the first element in the list. append(temp); //Appends it to the end of the list. moveToStart(); //Makes the current move to the first position. } }