TreeSet的第二种排序方式，当元素自身不具备比较性时或者具备的比较性不是需要的这时就需要让集合自身具备比较性，在集合初始化 就有了比较方式 comparator构造一个新的空TreeSet他根据指定的比较器进行排序

class student implements Comparable
{private String name;
private int age;
student(String name,int age)
{
this.name=name;
this.age=age;
}
public int compareTo(Object obj)
{if(!(obj instanceof student))
throw new RuntimeException("不是学生对象");
  student s=(student)obj;
int num=new Integer(this.getAge()).compareTo(new Integer(s.getAge()));
if(num==0)
{
return this.name.compareTo(s.name);
}
public String getName()
{
return name;
}
public int getAge()
{
return age;
}
}
class TreeSetDemo
{
public static void main(String[] args)
{
  TreeSet ts=new TreeSet();
  ts.add(new student("lisi08",20));
  ts.add(new student("lisi07 ",20));
  ts.add(new student("lisi02",22));
  ts.add(new student("lisi09",25));
  ts.add(new student("lisi007",28));
  ts.add(new student("lisi05",29));
  Iterator it=ts.iterator();
  while(it.hasNext())
  {student stu=(student)it.next();
  System.out.println(stu.getName()+"...."+stu.getAge());
   }
}
}
class myCompare implements comparator
{public int compare(Object o1,Object o2)
{Student s1=(student)o1;
Student s2=(student)o2;
int num=s.getName.compareTo(s2.getName);
if(num==0)
{
return new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
}
}


}

学习了，感谢分享！！！