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Copy pathIteratorTest.java
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164 lines (148 loc) · 3.24 KB
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package Iterator;
import java.lang.reflect.Array;
/**
* 迭代模式测试
* @author baitp
*
*/
public class IteratorTest {
public static void main(String[] args) {
/*ArrayList<String> arrayList = new ArrayList<>();
arrayList.add("ni");
arrayList.add("hao");
AbIterator<String> it = arrayList.iterator();
while(it.hasNext()) {
System.out.println(it.next());
}*/
LinkList<String> linkList = new LinkList<>();
linkList.add("ni");
linkList.add("hao");
AbIterator<String> it2 = linkList.iterator();
while(it2.hasNext()) {
System.out.println(it2.next());
}
}
}
/**
* 抽象集合，相当于Aggregate角色
* @author baitp
*/
interface AbList<T>{
public AbIterator<T> iterator();
}
/**
* 抽象迭代器，相当于Iterator角色
* @author baitp
*/
interface AbIterator<T>{
public boolean hasNext();
public T next();
}
/**
* 具体集合1，相当于ConcreteAggregate角色
* 内部使用数组
* @author baitp
*/
class ArrayList<T> implements AbList<T>{
private T[] ts;
private int defaultSize = 10;
private int realSize = 0;
private int addIndex = 0;
public ArrayList() {}
public ArrayList(int size) {
realSize = size;
}
@SuppressWarnings("unchecked")
public void add(T t) {
if(null == ts) {
ts = (T[])Array.newInstance(t.getClass(), 0 == realSize?defaultSize:realSize);
}
ts[addIndex++] = t;
addIndex %= ts.length;
}
@Override
public AbIterator<T> iterator() {
return new ArrayListIterator<T>();
}
/**
* 可以访问到具体集合的迭代器，一般使用内部类实现
* 不一定要持有集合，只要可以访问到集合对象即可，jdk的ArrayList也是使用此种方式实现。
* @author baitp
*/
class ArrayListIterator<E> implements AbIterator<E>{
private int index = 0;
@Override
public boolean hasNext() {
return index != ts.length-1 && null != ts[index];
}
@SuppressWarnings("unchecked")
@Override
public E next() {
return (E) ts[index++];
}
}
}
/**
* 具体集合2，相当于ConcreteAggregate角色
* 内部使用链表
* @author baitp
*/
class LinkList<T> implements AbList<T>{
Node<T> head;
Node<T> index;
public void add(T value) {
if(null == head) {
index = (head = new Node<T>(value,null));
}else {
index.next = new Node<T>(value,null);
index = index.next;
}
}
@Override
public AbIterator<T> iterator() {
return new LinkListIterator<T>();
}
/**
* 可以访问到具体集合的迭代器，一般使用内部类实现
* @author baitp
*/
class LinkListIterator<E> implements AbIterator<E>{
@SuppressWarnings("unchecked")
private Node<E> itIndex = (LinkList<T>.Node<E>) head;
@Override
public boolean hasNext() {
return itIndex != null;
}
@Override
public E next() {
E value = itIndex.getValue();
itIndex = itIndex.next;
return value;
}
}
/**
* 链表的节点类
* @author baitp
*/
class Node<E>{
E value;
Node<E> next;
public E getValue() {
return value;
}
public void setValue(E value) {
this.value = value;
}
public Node<E> getNext() {
return next;
}
public void setNext(Node<E> next) {
this.next = next;
}
public Node(E value, LinkList<T>.Node<E> next) {
super();
this.value = value;
this.next = next;
}
}
}