zoukankan      html  css  js  c++  java

  • 【java】ArrayList、Iterator用法

     1 package com.tn.collect;
 2 
 3 import java.util.ArrayList;
 4 import java.util.Iterator;
 5 
 6 class Product{
 7     public Product() {
 8         super();
 9         // TODO Auto-generated constructor stub
10     }
11     public Product(int id, String name, int price) {
12         // TODO Auto-generated constructor stub
13         setId(id);
14         setName(name);
15         setPrice(price);
16     }
17     private int id;
18     private String name;
19     private double price;
20     public int getId() {
21         return id;
22     }
23     public void setId(int id) {
24         this.id = id;
25     }
26     public String getName() {
27         return name;
28     }
29     public void setName(String name) {
30         this.name = name;
31     }
32     public double getPrice() {
33         return price;
34     }
35     public void setPrice(double price) {
36         this.price = price;
37     }
38     @Override
39     public String toString() {
40         return "Product [id=" + id + ", name=" + name + ", price=" + price
41                 + "]";
42     }
43 }
44 public class ArrayListLearning {
45     public static void main(String[] args){
46         Product product1=new Product(1001,"奇瑞",99999);
47         Product product2=new Product(1002,"江淮",88888);
48         Product product3=new Product(1003,"比亚迪",77777);
49         ArrayList arrayList=new ArrayList();
50         arrayList.add(product1);
51         arrayList.add(product2);
52         arrayList.add(product3);
53         System.out.println(arrayList);//会打印容器中每个对象的toString
54         System.out.println(arrayList.size());
55         Object object=arrayList.get(0);
56         System.out.println(object);
57         Product product=(Product)arrayList.get(0);
58         System.out.println(arrayList.get(0));
59         Product product4=new Product(1004,"力帆",66666);
60         Product product5=new Product(1005,"吉利",55555);
61         Product productx=new Product(1005,"吉利",55555);
62         ArrayList<Product> list=new ArrayList<Product>();
63         list.add(product4);
64         list.add(product5);
65         Product product6=list.get(0);
66         System.out.println(product6);
67         
68         //遍历方法一：
69         for(int i=0;i<list.size();i++){
70             Product pro=list.get(i);
71             System.out.println(pro);
72         }
73         
74         //遍历方法二：
75         Iterator<Product> iterator=list.iterator();
76         while(iterator.hasNext()){
77             Product pro=iterator.next();
78         }
79         
80         //遍历方法三：
81         for(Object obj:list){
82             Product pro=(Product)obj;
83         }
84         
85         System.out.println(list.contains(product5));
86         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
87     }
88 }
    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

      1 package com.tn.collect;
  2 
  3 import java.util.ArrayList;
  4 import java.util.Iterator;
  5 
  6 class Product{
  7     @Override
  8     public boolean equals(Object obj) {
  9         if (this == obj)
 10             return true;
 11         if (obj == null)
 12             return false;
 13         if (getClass() != obj.getClass())
 14             return false;
 15         Product other = (Product) obj;
 16         if (id != other.id)
 17             return false;
 18         return true;
 19     }
 20     public Product() {
 21         super();
 22         // TODO Auto-generated constructor stub
 23     }
 24     public Product(int id, String name, int price) {
 25         // TODO Auto-generated constructor stub
 26         setId(id);
 27         setName(name);
 28         setPrice(price);
 29     }
 30     private int id;
 31     private String name;
 32     private double price;
 33     public int getId() {
 34         return id;
 35     }
 36     public void setId(int id) {
 37         this.id = id;
 38     }
 39     public String getName() {
 40         return name;
 41     }
 42     public void setName(String name) {
 43         this.name = name;
 44     }
 45     public double getPrice() {
 46         return price;
 47     }
 48     public void setPrice(double price) {
 49         this.price = price;
 50     }
 51     @Override
 52     public String toString() {
 53         return "Product [id=" + id + ", name=" + name + ", price=" + price
 54                 + "]";
 55     }
 56 }
 57 public class ArrayListLearning {
 58     public static void main(String[] args){
 59         Product product1=new Product(1001,"奇瑞",99999);
 60         Product product2=new Product(1002,"江淮",88888);
 61         Product product3=new Product(1003,"比亚迪",77777);
 62         ArrayList arrayList=new ArrayList();
 63         arrayList.add(product1);
 64         arrayList.add(product2);
 65         arrayList.add(product3);
 66         System.out.println(arrayList);//会打印容器中每个对象的toString
 67         System.out.println(arrayList.size());
 68         Object object=arrayList.get(0);
 69         System.out.println(object);
 70         Product product=(Product)arrayList.get(0);
 71         System.out.println(arrayList.get(0));
 72         Product product4=new Product(1004,"力帆",66666);
 73         Product product5=new Product(1005,"吉利",55555);
 74         Product productx=new Product(1005,"吉利",55555);
 75         ArrayList<Product> list=new ArrayList<Product>();
 76         list.add(product4);
 77         list.add(product5);
 78         Product product6=list.get(0);
 79         System.out.println(product6);
 80         
 81         //遍历方法一：
 82         for(int i=0;i<list.size();i++){
 83             Product pro=list.get(i);
 84             System.out.println(pro);
 85         }
 86         
 87         //遍历方法二：
 88         Iterator<Product> iterator=list.iterator();
 89         while(iterator.hasNext()){
 90             Product pro=iterator.next();
 91         }
 92         
 93         //遍历方法三：
 94         for(Object obj:list){
 95             Product pro=(Product)obj;
 96         }
 97         
 98         System.out.println(list.contains(product5));
 99         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
100     }
101 }
    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
  • 相关阅读:
    [学习笔记] SSD代码笔记 + EifficientNet backbone 练习
    [论文理解] CornerNet: Detecting Objects as Paired Keypoints
    [torch] torch.contiguous
    [tensorflow] tf2.0 简单例子
    [大坑]Could not create cudnn handle: CUDNN_STATUS_INTERNAL_ERROR
    本机Jenkins的使用
    安全工具acunetix使用
    cv2.matchTemplate()函数的应用,匹配图片后画出矩形
    python将PNG格式的图片转化成为jpg
    Python实现FTP文件的上传和下载
  • 原文地址：https://www.cnblogs.com/xiongjiawei/p/6601837.html
Copyright © 2011-2022 走看看