集合框架-泛型在集合中的应用 

 1 package cn.itcast.p1.generic.demo;
 2 
 3 import java.util.Iterator;
 4 import java.util.TreeSet;
 5 
 6 import cn.itcast.p2.bean.Person;
 7 import cn.itcast.p3.comparator.ComparatorByName;
 8 
 9 public class GenericDemo2 {
10 
11     public static void main(String[] args) {
12         // TODO Auto-generated method stub
13         TreeSet<Person> ts = new TreeSet<Person>(new ComparatorByName());
14         ts.add(new Person("lisi8",21));
15         ts.add(new Person("lisi3",23));
16         ts.add(new Person("lisi",21));
17         ts.add(new Person("lis0",20));
18         
19         
20         Iterator<Person> it = ts.iterator();
21         
22         while(it.hasNext()) {
23             Person p = it.next();
24             System.out.println(p.getName()+":"+p.getAge());
25         }
26     }
27 
28 }
View Code
 1 package cn.itcast.p2.bean;
 2 
 3 import java.util.Comparator;
 4 
 5 public class Person implements Comparable<Person>{
 6     private String name;
 7     private int age;
 8     
 9     
10     public Person() {
11         super();
12         // TODO Auto-generated constructor stub
13     }
14     
15     public Person(String name, int age) {
16         super();
17         this.name = name;
18         this.age = age;
19     }
20     public int compareTo(Person p) {//指定比较类型，传入比较类型
21 //        Person p= (Person)obj;
22         int temp = this.age-p.age;
23         return temp==0?this.name.compareTo(p.name):temp;
24     }
25     
26     
27 //    @Override
28 //    public boolean equals(Object obj) {//不能把Object改为Person，equals方法来自Object，Object没有定义泛型
29 //        // TODO Auto-generated method stub
30 //        if (this == obj) {
31 //            return true;
32 //        }
33 //        if (!(obj instanceof Person)) {
34 //            throw new RuntimeException()
35 //        }
36 //        Person p = (Person)obj;
37 //        return super.equals(obj);
38 //    }
39     /*
40      * @Override public int hashCode() { final int prime = 31; int result = 1;
41      * result = prime * result + age; result = prime * result + ((name == null) ? 0
42      * : name.hashCode()); return result; }
43      * 
44      * @Override public boolean equals(Object obj) { if (this == obj) return true;
45      * if (obj == null) return false; if (getClass() != obj.getClass()) return
46      * false; Person other = (Person) obj; if (age != other.age) return false; if
47      * (name == null) { if (other.name != null) return false; } else if
48      * (!name.equals(other.name)) return false; return true; }//alt+shift+s
49      * hashCode和equals
50      */
51     public String getName() {
52         return name;
53     }
54     public void setName(String name) {
55         this.name = name;
56     }
57     public int getAge() {
58         return age;
59     }
60     public void setAge(int age) {
61         this.age = age;
62     }
63     
64 }
Person
 1 package cn.itcast.p3.comparator;
 2 
 3 import java.util.Comparator;
 4 
 5 import cn.itcast.p2.bean.Person;
 6 
 7 public class ComparatorByName implements Comparator<Person> {//ctrl+1快速实现方法
 8 
 9     @Override
10     public int compare(Person o1, Person o2) {
11         // TODO Auto-generated method stub
12         int temp = o1.getName().compareTo(o2.getName());
13         return temp==0?o1.getAge()-o2.getAge():temp;
14     }
15     
16 }
ComparatorByName

 

posted @ 2021-10-24 14:14  doremi429  阅读(26)  评论(0)  编辑  收藏  举报