迭代器模式
java迭代器模式,也叫java iterator模式,下面举个以模仿java的collecton、ArrayList、LinckedList为例
需要建立的类关系图
1案例代码
定义一个collection接口
/**
* Created by td on 2017/8/28.
* java迭代器模式,也叫java iterator模式。
* 举个实例 模仿java的collecton、ArrayList、LinckedList
*/
public interface Collection<E> {
public void add(E e);
public int size();
public Iterator iterator();
}
实现ArrayList
import java.util.*;
/**
* Created by td on 2017/8/28.
*/
public class ArratList<E> implements Collection<E> {
//先给定一个长度为10的数组
Object [] objects = new Object[10];
//冗余一个数组,方便判断数组是否满了和集合大小
int index = 0;
//添加元素
@Override
public void add(E e) {
//说明数组满了
if (index==objects.length){
Object [] newObjects = new Object[objects.length*2];
System.arraycopy(objects,0,newObjects,0,objects.length);
objects = newObjects;
}
objects[index] = e;
index++;
}
@Override
public int size() {
return index;
}
@Override
public Iterator iterator() {
return new ArrayListIterator();
}
private class ArrayListIterator implements Iterator{
private int currentIndex = 0;
@Override
public Object next() {
E e = (E) objects[currentIndex];
currentIndex++;
return e;
}
@Override
public boolean hasNext() {
if (currentIndex>=index) {
return false;
}
return true;
}
}
}
实现LinkedList
import javax.swing.table.TableCellEditor;
import java.util.*;
/**
* Created by td on 2017/8/28.
*/
public class LinkedList<E> implements Collection<E>{
private Node head;
private Node tail;
private int size;
@Override
public void add(E e) {
Node node = new Node(e,null);
if (head==null){
head = node;
tail = node;
size++;
}else {
tail.setNext(node);
tail = node;
size++;
}
}
@Override
public int size() {
return size;
}
@Override
public Iterator iterator() {
return new LinkedListIterator();
}
private class LinkedListIterator implements Iterator{
private Node currentNode = head;
@Override
public Object next() {
currentNode = currentNode.getNext();
return currentNode.getData();
}
@Override
public boolean hasNext() {
if (currentNode.getNext()==null){
return false;
}
return true;
}
}
}
定义Node
/**
* Created by td on 2017/8/28.
*/
public class Node {
private Object data;
private Node next;
public Node(Object data, Node next) {
this.data = data;
this.next = next;
}
public Object getData() {
return data;
}
public void setData(Object data) {
this.data = data;
}
public Node getNext() {
return next;
}
public void setNext(Node next) {
this.next = next;
}
}
定义迭代器接口
/**
* Created by td on 2017/8/28.
*/
public interface Iterator {
public Object next();
public boolean hasNext();
}
集合中装的对象,用于测试迭代器
/**
* Created by td on 2017/8/28.
*/
public class Person {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
定义迭代器测试类,进行测试
/**
* Created by td on 2017/8/28.
*/
public class CollectionTest {
public static void main(String[] args) {
Collection<Person> collection = new LinkedList<Person>();
for (int i=0;i<10;i++){
Person person = new Person(i+"name",i);
collection.add(person);
}
System.out.println(collection.size());
Iterator iterator = collection.iterator();
while (iterator.hasNext()){
System.out.println(iterator.next().toString());
}
System.out.println("=========================");
collection = new ArratList<Person>();
for (int i=0;i<10;i++){
Person person = new Person(i+"name",i);
collection.add(person);
}
iterator = collection.iterator();
while (iterator.hasNext()){
System.out.println(iterator.next());
}
}
}
测试结果
10
Person{name='1name', age=1}
Person{name='2name', age=2}
Person{name='3name', age=3}
Person{name='4name', age=4}
Person{name='5name', age=5}
Person{name='6name', age=6}
Person{name='7name', age=7}
Person{name='8name', age=8}
Person{name='9name', age=9}
=========================
Person{name='0name', age=0}
Person{name='1name', age=1}
Person{name='2name', age=2}
Person{name='3name', age=3}
Person{name='4name', age=4}
Person{name='5name', age=5}
Person{name='6name', age=6}
Person{name='7name', age=7}
Person{name='8name', age=8}
Person{name='9name', age=9}
网友评论