单链表反转(Singly Linked Lists in Java)

　
package dsa.linkedlist;  
  
public class Node<E>{  
 E data;  
 Node<E> next;  
} 

package dsa.linkedlist;  
  
public class ReverseLinkedListRecursively {  
  
    public static void main(String args[]) {  
        ReverseLinkedListRecursively reverser = new ReverseLinkedListRecursively();  
        SinglyLinkedList<Integer> originalList = reverser.getLabRatList(10);  
        System.out.println("Original List : " + originalList.toString());  
        originalList.start = reverser.reverse(originalList.start);  
        System.out.println("Reversed List : " + originalList.toString());  
    }  
  
    public Node<Integer> reverse(Node<Integer> list) {  
        if (list == null || list.next == null)  
            return list;  
        Node<Integer> nextItem = list.next;  
        list.next = null;  
        Node<Integer> reverseRest = reverse(nextItem);  
        nextItem.next = list;  
        return reverseRest;  
    }  
  
    private SinglyLinkedList<Integer> getLabRatList(int count) {  
        SinglyLinkedList<Integer> sampleList = new SinglyLinkedList<Integer>();  
        for (int i = 0; i < count; i++) {  
            sampleList.add(i);  
        }  
        return sampleList;  
    }  
}  
/* 
 * SAMPLE OUTPUT Original List : 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 Reversed List : 9, 
 * 8, 7, 6, 5, 4, 3, 2, 1, 0 
 */  

package dsa.linkedlist;  
  
/** 
 * This is a singly linked list with no prev pointer. 
 * @author Braga 
 * @param <E> 
 */  
public class SinglyLinkedList<E> {  
   
 Node<E> start;  
 int size;  
   
 public SinglyLinkedList(){  
  start = null;  
  size = 0;  
 }  
   
 //insertAtLast  
 public void add(E data){  
  insertAtLast(data);  
 }  
   
 public void insertAtLast(E data){  
  if(size==0){  
   start = new Node<E>();  
   start.next = null;  
   start.data = data;  
  }else{  
   Node<E> currentNode = getNodeAt(size-1);  
   Node<E> newNode = new Node<E>();  
   newNode.data = data;  
   newNode.next = null;  
   currentNode.next = newNode;  
  }  
  size++;  
 }  
   
 public void insertAtFirst(E data){  
  if(size==0){  
   start = new Node<E>();  
   start.next = null;  
   start.data = data;  
  }else{  
   Node<E> newNode = new Node<E>();  
   newNode.data = data;  
   newNode.next = start;  
   start = newNode;  
  }  
  size++;  
 }  
   
 public Node<E> getNodeAt(int nodePos) throws ArrayIndexOutOfBoundsException{  
  if(nodePos>=size || nodePos<0){  
   throw new ArrayIndexOutOfBoundsException();  
  }  
  Node<E> temp = start;//Move pointer to front  
  int counter = 0;  
  for(;counter<nodePos;counter++){  
   temp = temp.next;  
  }  
  return temp;  
 }  
   
 public void insertAt(int position, E data){  
  if(position == 0){  
   insertAtFirst(data);  
  }else if(position==size-1){  
   insertAtLast(data);  
  }else{  
   Node<E> tempNode = getNodeAt(position-1);  
   Node<E> newNode = new Node<E>();  
   newNode.data = data;  
   newNode.next = tempNode.next;  
   tempNode.next = newNode;  
   size++;  
  }  
 }  
   
 public Node<E> getFirst(){  
  return getNodeAt(0);  
 }  
   
 public Node<E> getLast(){  
  return getNodeAt(size-1);  
 }  
   
 public E removeAtFirst(){  
  if(size==0){  
   throw new ArrayIndexOutOfBoundsException();  
  }  
  E data = start.data;  
  start = start.next;  
  size--;  
  return data;  
 }  
   
 public E removeAtLast(){  
  if(size==0){  
   throw new ArrayIndexOutOfBoundsException();  
  }  
  Node<E> tempNode = getNodeAt(size-2);  
  E data = tempNode.next.data;  
  tempNode.next = null;  
  size--;  
  return data;  
 }  
   
 public E removeAt(int position){  
  if(position==0){  
   return removeAtFirst();  
  }else if(position == size-1){  
   return removeAtLast();  
  }else{  
   Node<E> tempNode = getNodeAt(position-1);  
   E data = tempNode.next.data;  
   tempNode.next = tempNode.next.next;  
   size--;  
   return data;  
  }  
 }  
   
 public int size(){  
  return size;  
 }  
   
 public String toString(){  
  if(size==0){  
   return "";  
  }else{  
   StringBuilder output = new StringBuilder();  
   Node<E> tempNode = start;  
   while(tempNode.next!=null){  
    output.append(tempNode.data).append(", ");  
    tempNode = tempNode.next;  
   }  
   output.append(tempNode.data);  
   return output.toString();  
  }  
 }  
   
}