I have been trying to teach this myself, but I judt don't get it. I have 10 books with ISBN number, title, name of author. The linked list should display the books sorted by ISBN. I hope this collections.sort is correct:
import java.util*;
public class Sort
{
public class Sort
{
List<integer> MYLIST new ArrayList<integer>();
//add integers 0 through 9 to the list
for (int count = 0; count < 10; count++)
MYLIST.add(count);
// display the list
System.out.println(List Contents:");
System.out.println(MYLIST);
// sort in acending order
Collections.sort(MYLIST);
//display the list
System.out.println("\Sorted List:");
System.out.println(MYLIST);
}
}
The linked list is this:
class LinkedList1
{
private class Node
{
String value;
Node next;
Node(String val, Node n)
{
value = val;
next = n;
}
Node(String val)
{
// Call the other (sister) constructor.
this(val, null);
}
}
private Node first; // list head
private Node last; // last element in list
/**
Constructor.
*/
public LinkedList1()
{
first = null;
last = null;
}
/**
The isEmpty method checks to see
if the list is empty.
@return true if list is empty,
false otherwise.
*/
public boolean isEmpty()
{
return first == null;
}
public int size()
{
int count = 0;
Node p = first;
while (p != null)
{
// There is an element at p
count ++;
p = p.next;
}
return count;
}
public void add(String e)
{
if (isEmpty())
{
first = new Node(e);
last = first;
}
else
{
// Add to end of existing list
last.next = new Node(e);
last = last.next;
}
}
public void add(int index, String e)
{
if (index < 0 || index > size())
{
String message = String.valueOf(index);
throw new IndexOutOfBoundsException(message);
}
// Index is at least 0
if (index == 0)
{
// New element goes at beginning
first = new Node(e, first);
if (last == null)
last = first;
return;
}
// Set a reference pred to point to the node that
// will be the predecessor of the new node
Node pred = first;
for (int k = 1; k <= index - 1; k++)
{
pred = pred.next;
}
// Splice in a node containing the new element
pred.next = new Node(e, pred.next);
// Is there a new last element ?
if (pred.next.next == null)
last = pred.next;
}
public String toString()
{
StringBuilder strBuilder = new StringBuilder();
// Use p to walk down the linked list
Node p = first;
while (p != null)
{
strBuilder.append(p.value + "\n");
p = p.next;
}
return strBuilder.toString();
}
public String remove(int index)
{
if (index < 0 || index >= size())
{
String message = String.valueOf(index);
throw new IndexOutOfBoundsException(message);
}
String element; // The element to return
if (index == 0)
{
// Removal of first item in the list
element = first.value;
first = first.next;
if (first == null)
last = null;
}
else
{
// To remove an element other than the first,
// find the predecessor of the element to
// be removed.
Node pred = first;
// Move pred forward index - 1 times
for (int k = 1; k <= index -1; k++)
pred = pred.next;
// Store the value to return
element = pred.next.value;
// Route link around the node to be removed
pred.next = pred.next.next;
// Check if pred is now last
if (pred.next == null)
last = pred;
}
return element;
}
public boolean remove(String element)
{
if (isEmpty())
return false;
if (element.equals(first.value))
{
// Removal of first item in the list
first = first.next;
if (first == null)
last = null;
return true;
}
// Find the predecessor of the element to remove
Node pred = first;
while (pred.next != null &&
!pred.next.value.equals(element))
{
pred = pred.next;
}
// pred.next == null OR pred.next.value is element
if (pred.next == null)
return false;
// pred.next.value is element
pred.next = pred.next.next;
// Check if pred is now last
if (pred.next == null)
last = pred;
return true;
}
public static void main(String [] args)
{
LinkedList1 ll = new LinkedList1();
ll.add("Book1, Mr. Y, 12345");
ll.add("Book2, Mrs. X, 28439");
ll.add("Book3, Mr.XY, 39482");
ll.add("Book4, Mrs. ZYZ, 38372");
ll.add("Book5, Mr. UY, 93827");
System.out.println("The members of the list are:");
System.out.print(ll);
}
}
Is this correct? If so, how do I sort it when I have more than one item in the node? How does it know which one the ISBN is. Also, how does collection.sort get the content? As you can see, right now I tell it what the numbers are going to be. I have not figured out how it gets it itself.
I don't get it. Can someone please show me how to do this?
