Java实现泛型链表

import java.util.Iterator;

public class LinkList<V> implements Iterable<V> {

 Data<V> first;
 Data<V> last;
 Data<V> current;
 int count;
 
 public LinkList() {
  
 }
 
 public boolean add(V obj)
 {
  boolean ret = false;
  Data<V> data = new Data<V>(obj);
  if(first == null)
  {
   first = data;
   last  = data;
   current = data;
   ret = true;
  }
  else
  {
   last.next = data;
   data.previous = last;
   last = data;
   last.next = null;
   ret = true;
  }
  count++;
  return ret;
 }
 
 public V get(int index)
 {
  return getData(index).data;
 }
 
 public V getFirst()
 {
  return first.data;
 }
 
 public V getLast()
 {
  return last.data;
 }
 
 public int indexOfx(V obj)
 {
  int index = -1;
  current = first;
  while(count-- > 0)
  {
   if(current.data.equals(obj))
   {
    ++index;
    break;
   }
   current = current.next;
  }
  return index;
 }
 
 public boolean removeAt(int index)
 {
  boolean ret = false;
  if(checkIndex(index))return ret;
  if(index == 0)
  {
   first = first.next;
   first.previous = null;
   ret = true;
  }
  else if(index == count - 1)
  {
   last = last.previous;
   last.next = null;
   ret = true;
  }
  else
  {
   Data<V> _f,_l;
   current = getData(index);
   System.out.println(current.data);
   _f = current.previous;
   _l = current.next;
   _f.next = _l;
   _l.previous = _f;
   ret = true;
  }
  
  count--;
  
  return ret;
 }
 
 public V remove(V obj)
 {
  current = first;
  int i = -1;
  while(i < count)
  {
   i++;
   if(current.data.equals(obj))break;
   current = current.next;
  }
  removeAt(i);
  return current.data;
 }
 
 public boolean insert(int index , V obj)
 {
  boolean ret = false;
  Data<V> data = new Data<V>(obj);
  if(index == 0)
  {
   current = first;
   first = data;
   first.next = current;
   first.previous = null;
  }
  else if(index == count -1)
  {
   current = last;
   last = data;
   last.previous = current;
   last.next = null;
  }
  else
  {
   Data<V> _u,_l;
   current = getData(index);
   _u = current.previous;
   _l = current;
   _u.next = data;
   data.previous = _u;
   _l.previous = data;
   data.next = _l;
  }
  count++;
  return ret;
 }
 
 public Data<V> getData(int index)
 {
  if(checkIndex(index))throw new ArrayIndexOutOfBoundsException("数组越界！");
  current = first;
  while(index-- > 0)
   current = current.next;
  return current;
 }
 
 public boolean checkIndex(int i)
 {
  boolean ret = false;
  if(i < 0 || i > count - 1)ret = true;
  return ret;
 }

 class Data<T>
 {
  T data;
  Data<T> previous;
  Data<T> next;
  Data(T t)
  {
   this.data = t;
  }
 }
 
 // 实现Iterable 接口可使用 for-each 类型循环厉遍。
 @SuppressWarnings("unchecked")
 public Iterator iterator() {
  return new Itr();
 }
 
 class Itr implements Iterator
 {
  int cursor = 0;
  int lastRet = -1;
  
  public boolean hasNext() {
   boolean ret = false;
   if(cursor != count)ret = true;
   return ret;
  }

  public Object next() {
   return getData(cursor++).data;
  }

  public void remove() {
  }

 }

}