LinkedHashSet集合特点：哈希表和链表实现的Set接口，具有可预测的迭代次序。由链表保证元素有序，元素的存储和取出是一致的。由哈希表保证元素唯一，也就是说没有重复的元素。
TreeSet集合特点：元素按照一定的规则进行排序，具体排序方式取决于构造方法。TreeSet()：根据其元素的自然排序进行排序。TreeSet(Comparator comparator):根据指定的比较器进行排序。其余和``Set集合特点一样. 自然排序实现Comparable接口，重写compareTo`方法.
比较器排序：使用匿名内部类

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package 集合;

public class Student implements Comparable<Student>{
private String name;
private int 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 int hashCode() {
	final int prime = 31;
	int result = 1;
	result = prime * result + age;
	result = prime * result + ((name == null) ? 0 : name.hashCode());
	return result;
}
@Override
public boolean equals(Object obj) {
	if (this == obj)
		return true;
	if (obj == null)
		return false;
	if (getClass() != obj.getClass())
		return false;
	Student other = (Student) obj;
	if (age != other.age)
		return false;
	if (name == null) {
		if (other.name != null)
			return false;
	} else if (!name.equals(other.name))
		return false;
	return true;
}
public Student() {
	super();
	// TODO Auto-generated constructor stub
}
public Student(String name, int age) {
	super();
	this.name = name;
	this.age = age;
}
@Override
public int compareTo(Student o) {
	// TODO Auto-generated method stub
	//return 1;//认为s1元素与s2元素相等 。return 1则认为s1比s2大 ，return -1则认为s1比s2小
	int num=this.age-o.age;
	int num2=num==0?this.name.compareTo(o.name):num;
	return num2;
}

}

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package 集合;

import java.util.TreeSet;

public class TreeSetDemo {
	public static void main(String[] args) {
		  TreeSet<Student> st=new TreeSet<Student>();
		Student s1=new Student("1",11);
		   Student s2=new Student("11",11);
		   Student s3=new Student("2",22);
		   Student s4=new Student("3",33);
		   
		 
		   st.add(s1);
		   st.add(s2);
		   st.add(s3);
		   st.add(s4);
		   
		   for(Student s:st) {
			   System.out.println("年龄排序："+s.getAge());
		   }
	}
}
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年龄排序：11
年龄排序：11
年龄排序：22
年龄排序：33

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TreeSet<Student> st=new TreeSet<Student>(new Comparator<Student>() {

		@Override
		public int compare(Student o1, Student o2) {
			// TODO Auto-generated method stub
			int num=o1.getAge()-o2.getAge();
			int num2=num==0?o1.getName().compareTo(o2.getName()):num;
			return num2;
		}
	});