@Test
    public void test7(){
        HashSet set = new HashSet();
        set.add(456);
        set.add(123);
        set.add(123);
        set.add("AA");
        set.add(new Person("Twq",23));
        set.add(new Person("Twq",23));
        set.add("CC");
        Iterator iterator = set.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }

 @Test
    public void test8(){
        TreeSet set = new TreeSet();
        //添加失败的原因就是不能添加不同类的对象
//        treeSet.add(123);
//        treeSet.add(456);
//        treeSet.add("aaa");
        set.add(32);
        set.add(-12);
        set.add(12);
        set.add(123);
        Iterator iterator = set.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }

    }

 @Test
    public void test8(){
        TreeSet set = new TreeSet();
        //添加失败的原因就是不能添加不同类的对象
//        treeSet.add(123);
//        treeSet.add(456);
//        treeSet.add("aaa");
        //举例一：
//        set.add(32);
//        set.add(-12);
//        set.add(12);
//        set.add(123);
        //举例二：
        set.add(new Person("Twq",23));
        set.add(new Person("Jerry",12));
        set.add(new Person("Tom",30));
        set.add(new Person("Twq",18));
        set.add(new Person("Mack",32));
        Iterator iterator = set.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }

package com.Tang.set;

public class Person implements Comparable{
    private String name;
    private int age;

    public Person() {
    }

    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 +
                '}';
    }
    //向collection接口的实现类的对象中添加数据obj时，要求obj所在的类要重写equals()方法
    @Override
    public boolean equals(Object o) {
        System.out.println("Person equal()...");
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        Person person = (Person) o;

        if (age != person.age) return false;
        return name != null ? name.equals(person.name) : person.name == null;
    }

    @Override
    public int compareTo(Object o) {
        if(o instanceof Person){
            Person p = (Person) o;
//            return this.name.compareTo(p.name);
            int compare = this.name.compareTo(p.name);
            if(compare != 0)//名字不相同，按名字从小到大排序
                return compare;
            else{//当名字相同时按年龄从小到大排序
                return Integer.compare(this.age,p.age);
            }
        }
        else{
            throw new RuntimeException("输入数据有误");
        }
    }

//    @Override
//    public int hashCode() {
//        int result = name != null ? name.hashCode() : 0;
//        result = 31 * result + age;
//        return result;
//    }
}

@Test
    public void test9(){
        Comparator com = new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                //按年龄从大到小排序
                if(o1 instanceof Person && o2 instanceof Person){
                    Person p1 = (Person) o1;
                    Person p2 = (Person) o2;
                    return -Integer.compare(p1.getAge(),p2.getAge());
                }
                else
                    throw new RuntimeException("输入类型不一致");
            }
        };
        TreeSet set = new TreeSet(com);//传入参数com使得其按照指定的排序来
        set.add(new Person("Twq",23));
        set.add(new Person("Jerry",12));
        set.add(new Person("Tom",30));
        set.add(new Person("Twq",18));
        set.add(new Person("Mack",32));
        Iterator iterator = set.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }