TreeSet简单使用

仅仅是使用方法，非源码分析。

 1 public class Test {
 2
 3     public static void main(String[] args) {
 4         TreeSet<String> treeSet=new TreeSet<>();
 5         treeSet.add("Se");
 6         treeSet.add("Ald");
 7         treeSet.add("Boo");
 8         treeSet.add("CC");
 9         Iterator<String> iterator=treeSet.iterator();
10         while (iterator.hasNext()) {
11             String string = (String) iterator.next();
12             System.out.println(string);
13         }
14     }
15
16 }

输出：

Ald
Boo
CC
Se

使用TreeSet集合时，元素必须实现Comparable接口。

 1 public class Person implements Comparable<Person> {
 2     private String name;
 3     private int age;
 4
 5     public Person() {
 6         // TODO Auto-generated constructor stub
 7     }
 8
 9     public Person(String name, int age) {
10         this.name = name;
11         this.age = age;
12     }
13
14     public String getName() {
15         return name;
16     }
17
18     public void setName(String name) {
19         this.name = name;
20     }
21
22     public int getAge() {
23         return age;
24     }
25
26     public void setAge(int age) {
27         this.age = age;
28     }
29
30     @Override
31     public String toString() {
32         // TODO Auto-generated method stub
33         return "name:" + getName() + "  age:" + getAge();
34     }
35
36     /**
37      * 升序排列
38      */
39     @Override
40     public int compareTo(Person person) {
41         // TODO Auto-generated method stub
42         if (this.getAge() > person.getAge()) {
43             return 1;
44         } else if (this.getAge() == person.getAge()) {
45             return 0;
46         } else {
47             return -1;
48         }
49     }
50
51 }

测试类：

 1 public class Test {
 2
 3     public static void main(String[] args) {
 4         // TODO Auto-generated method stub
 5         TreeSet<Person> tSet = new TreeSet<>();
 6         tSet.add(new Person("shldom", 23));
 7         tSet.add(new Person("tom", 12));
 8         tSet.add(new Person("woa", 45));
 9         tSet.add(new Person("moe", 87));
10         Iterator<Person> iterator=tSet.iterator();
11         while(iterator.hasNext()){
12             System.out.println(iterator.next());
13         }
14     }
15
16 }

输出结果：

name:tom  age:12
name:shldom  age:23
name:woa  age:45
name:moe  age:87