【java】ArrayList、Iterator用法

 package com.tn.collect;

 import java.util.ArrayList;
 import java.util.Iterator;

 class Product{
     public Product() {
         super();
         // TODO Auto-generated constructor stub
     }
     public Product(int id, String name, int price) {
         // TODO Auto-generated constructor stub
         setId(id);
         setName(name);
         setPrice(price);
     }
     private int id;
     private String name;
     private double price;
     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public double getPrice() {
         return price;
     }
     public void setPrice(double price) {
         this.price = price;
     }
     @Override
     public String toString() {
         return "Product [id=" + id + ", name=" + name + ", price=" + price
                 + "]";
     }
 }
 public class ArrayListLearning {
     public static void main(String[] args){
         Product product1=new Product(1001,"奇瑞",99999);
         Product product2=new Product(1002,"江淮",88888);
         Product product3=new Product(1003,"比亚迪",77777);
         ArrayList arrayList=new ArrayList();
         arrayList.add(product1);
         arrayList.add(product2);
         arrayList.add(product3);
         System.out.println(arrayList);//会打印容器中每个对象的toString
         System.out.println(arrayList.size());
         Object object=arrayList.get(0);
         System.out.println(object);
         Product product=(Product)arrayList.get(0);
         System.out.println(arrayList.get(0));
         Product product4=new Product(1004,"力帆",66666);
         Product product5=new Product(1005,"吉利",55555);
         Product productx=new Product(1005,"吉利",55555);
         ArrayList<Product> list=new ArrayList<Product>();
         list.add(product4);
         list.add(product5);
         Product product6=list.get(0);
         System.out.println(product6);

         //遍历方法一：
         for(int i=0;i<list.size();i++){
             Product pro=list.get(i);
             System.out.println(pro);
         }

         //遍历方法二：
         Iterator<Product> iterator=list.iterator();
         while(iterator.hasNext()){
             Product pro=iterator.next();
         }

         //遍历方法三：
         for(Object obj:list){
             Product pro=(Product)obj;
         }

         System.out.println(list.contains(product5));
         System.out.println(list.contains(productx));//对象创建是两个，但实际应用中这两个对象应该是一个
     }
 }

ArrayList

运行结果：

[Product [id=1001, name=奇瑞, price=99999.0], Product [id=1002, name=江淮, price=88888.0], Product [id=1003, name=比亚迪, price=77777.0]]
3
Product [id=1001, name=奇瑞, price=99999.0]
Product [id=1001, name=奇瑞, price=99999.0]
Product [id=1004, name=力帆, price=66666.0]
Product [id=1004, name=力帆, price=66666.0]
Product [id=1005, name=吉利, price=55555.0]
true
false

---

 package com.tn.collect;

 import java.util.ArrayList;
 import java.util.Iterator;

 class Product{
     @Override
     public boolean equals(Object obj) {
         if (this == obj)
             return true;
         if (obj == null)
             return false;
         if (getClass() != obj.getClass())
             return false;
         Product other = (Product) obj;
         if (id != other.id)
             return false;
         return true;
     }
     public Product() {
         super();
         // TODO Auto-generated constructor stub
     }
     public Product(int id, String name, int price) {
         // TODO Auto-generated constructor stub
         setId(id);
         setName(name);
         setPrice(price);
     }
     private int id;
     private String name;
     private double price;
     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public double getPrice() {
         return price;
     }
     public void setPrice(double price) {
         this.price = price;
     }
     @Override
     public String toString() {
         return "Product [id=" + id + ", name=" + name + ", price=" + price
                 + "]";
     }
 }
 public class ArrayListLearning {
     public static void main(String[] args){
         Product product1=new Product(1001,"奇瑞",99999);
         Product product2=new Product(1002,"江淮",88888);
         Product product3=new Product(1003,"比亚迪",77777);
         ArrayList arrayList=new ArrayList();
         arrayList.add(product1);
         arrayList.add(product2);
         arrayList.add(product3);
         System.out.println(arrayList);//会打印容器中每个对象的toString
         System.out.println(arrayList.size());
         Object object=arrayList.get(0);
         System.out.println(object);
         Product product=(Product)arrayList.get(0);
         System.out.println(arrayList.get(0));
         Product product4=new Product(1004,"力帆",66666);
         Product product5=new Product(1005,"吉利",55555);
         Product productx=new Product(1005,"吉利",55555);
         ArrayList<Product> list=new ArrayList<Product>();
         list.add(product4);
         list.add(product5);
         Product product6=list.get(0);
         System.out.println(product6);

         //遍历方法一：
         for(int i=0;i<list.size();i++){
             Product pro=list.get(i);
             System.out.println(pro);
         }

         //遍历方法二：
         Iterator<Product> iterator=list.iterator();
         while(iterator.hasNext()){
             Product pro=iterator.next();
         }

         //遍历方法三：
         for(Object obj:list){
             Product pro=(Product)obj;
         }

         System.out.println(list.contains(product5));
         System.out.println(list.contains(productx));//对象创建是两个，但实际应用中这两个对象应该是一个
     }
 }

重写equals方法后

运行结果：

[Product [id=1001, name=奇瑞, price=99999.0], Product [id=1002, name=江淮, price=88888.0], Product [id=1003, name=比亚迪, price=77777.0]]
3
Product [id=1001, name=奇瑞, price=99999.0]
Product [id=1001, name=奇瑞, price=99999.0]
Product [id=1004, name=力帆, price=66666.0]
Product [id=1004, name=力帆, price=66666.0]
Product [id=1005, name=吉利, price=55555.0]
true
true