7-13 TreeSet自定义排序

import java.util.Comparator;
import java.util.TreeSet;
class Student{
	private String id;
	private String name;
	public Student(String id,String name) {
		this.id=id;
		this.name=name;
	}
	public String getId() {
		return id;
	}
	public String getName() {
		return name;
	}
	//重写toString方法
	public String toString() {
		return id+":"+name;
	}
}
public class Example {
public static void main(String[]args) {
	TreeSet ts=new TreeSet(new Comparator() {
		public int compare(Object o1,Object o2) {
			Student stu1=(Student)o1;
			Student stu2=(Student)o2;
			if(!stu1.getId().equals(stu2.getId())) {
				return stu1.getId().compareTo(stu2.getId());
			}
			else
				return stu1.getName().compareTo(stu2.getName());
		}
	});
	ts.add(new Student("2","Mary"));
	ts.add(new Student("1","Jack"));
	ts.add(new Student("3","Lisa"));
	ts.add(new Student("2","Lily"));
	System.out.println(ts);
}
}

运行结果：

[1:Jack, 2:Lily, 2:Mary, 3:Lisa]