import java.util.Iterator;
/**
* 類名:MyLinkedList 說明:LinkedList的基本實現
*/
public class MyLinkedList<AnyType> implements Iterable {
private int theSize = 0;
private int modCount = 0;
private Node<AnyType> beginMarker;
private Node<AnyType> endMarker;
private static class Node<AnyType> {
public Node(AnyType data, Node<AnyType> prev, Node<AnyType> next) {
this.data = data;
this.prev = prev;
this.next = next;
}
public AnyType data;
public Node<AnyType> prev;
public Node<AnyType> next;
}
public MyLinkedList() {
clear();
}
public void clear() {
beginMarker = new Node<AnyType>(null, null, null);
endMarker = new Node<AnyType>(null, beginMarker, null);
beginMarker.next = endMarker;
theSize = 0;
modCount++;
}
public boolean isEmpty() {
return theSize == 0;
}
public int size() {
return theSize;
}
public boolean add(AnyType x) {
add(theSize, x);
return true;
}
public void add(int index, AnyType x) {
addBefore(getNode(index), x);
}
public AnyType get(int index) {
return getNode(index).data;
}
private Node<AnyType> getNode(int index) {
if (index < 0 || index > theSize)
throw new IndexOutOfBoundsException();
Node<AnyType> p;
if (index < size() / 2) {
p = beginMarker.next;
for (int i = 0; i < index; i++) {
p = p.next;
}
} else {
p = endMarker;
for (int i = theSize; i > index; i--)
p = p.prev;
}
return p;
}
private void addBefore(Node<AnyType> p, AnyType x) {
Node<AnyType> newNode = new Node(x, p.prev, p);
newNode.prev.next = newNode;
p.prev = newNode;
theSize++;
modCount++;
}
private AnyType remove(Node<AnyType> p) {
AnyType removed = p.data;
p.prev.next = p.next;
p.next.prev = p.prev;
theSize--;
modCount++;
return removed;
}
public AnyType set(int index, AnyType x) {
AnyType old = getNode(index).data;
getNode(index).data = x;
return old;
}
public AnyType remove(int index) {
return remove(getNode(index));
}
@Override
public Iterator iterator() {
// TODO Auto-generated method stub
return new Iterator() {//匿名內部類實現,jdk裏是返回重新寫的一個private類。
private Node<AnyType> current = beginMarker.next;
private int expectedModCount = modCount;
private boolean okToRemove = false;
public boolean hasNext() {
return current != endMarker;
}
public AnyType next() {
if (modCount != expectedModCount) {
throw new java.util.ConcurrentModificationException();
}
if (!hasNext())
throw new java.util.NoSuchElementException();
AnyType d = current.data;
current = current.next;
okToRemove = true;
return d;
}
public void remove() {
if (modCount != expectedModCount) {
throw new java.util.ConcurrentModificationException();
}
if (!okToRemove)
throw new IllegalStateException();
MyLinkedList.this.remove(current.prev);
okToRemove = false;
expectedModCount++;
}
};
}
public String toString() {
String s = new String();
for (int i = 0; i < theSize; i++)
s += get(i) + " ";
return s;
}
/**
* 方法名:MyLinkedList.java 說明:測試
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
MyLinkedList<Integer> list = new MyLinkedList();
list.add(1);
list.add(2);
list.add(3);
list.add(4);
list.add(5);
System.out.println(list);
list.remove(1);
System.out.println(list);
list.set(1, 2);
System.out.println(list);
Iterator ite = list.iterator();
while (ite.hasNext()) {
System.out.println(ite.next() + " ");
}
}
}
JAVA類庫LinkList的基本實現
寫完調試了好久,邊界不好處理,詳細的請看JDK類庫,以下只是基本實現:
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