Set集合

public class UpdateStu implements Comparable<Object>{

    String name;
    long id;
    
    public UpdateStu(String name,long id) {
        // TODO Auto-generated constructor stub
        this.id = id;
        this.name = name;
    }
    
    public int compareTo(Object o) {
        UpdateStu upstu = (UpdateStu)o;
        int result = id > upstu.id? 1 : (id == upstu.id? 0 : -1);
        return result;
    }
    
    public String getString() {
        return name;
    }
    public void setString(String name) {
        this.name = name ;
    }
    
    public long getid() {
        return id;
    }
    public void setid(long id) {
        this.id = id;
    }
    
    
    public static void main(String[] args) {
        UpdateStu stu1 = new UpdateStu("李同学", 01011);
        UpdateStu stu2 = new UpdateStu("程同学", 01021);
        UpdateStu stu3 = new UpdateStu("王同学", 01051);
        UpdateStu stu4 = new UpdateStu("马同学", 01012);
        TreeSet<UpdateStu> tree = new TreeSet<>();
        tree.add(stu1);
        tree.add(stu2);
        tree.add(stu3);
        tree.add(stu4);
        Iterator<UpdateStu> it = tree.iterator();
        System.out.println("Set集合中的所有元素");
        while(it.hasNext()){
            UpdateStu stu = (UpdateStu)it.next();
            System.out.println(stu.getid() + " " + stu.getString());
        }
        it = tree.headSet(stu2).iterator();
        System.out.println("截取前面部分的集合");
        while(it.hasNext()){
            UpdateStu stu = (UpdateStu)it.next();
            System.out.println(stu.getid() + " " + stu.getString());
        }
        
        it = tree.subSet(stu2, stu3).iterator();
        System.out.println("截取中间部分的集合");
        while(it.hasNext()){
            UpdateStu stu = (UpdateStu)it.next();
            System.out.println(stu.getid() + " " + stu.getString());
        }
        
        
    }
    
}