使用TreeSet存储教室对象，教室对象包括教室号no,教室地址 address,教室容纳人数 count,使用教室号排序。遍历TreeSet.

首先，我们需要定义一个教室类，包括教室号no、教室地址address和教室容纳人数count。教室类需要实现Comparable接口，并重写compareTo方法，以实现按照教室号排序。

代码如下：

import java.util.TreeSet;

public class Classroom implements Comparable<Classroom>{
    private String no;
    private String address;
    private int count;

    public Classroom(String no, String address, int count) {
        this.no = no;
        this.address = address;
        this.count = count;
    }

    public String getNo() {
        return no;
    }

    public void setNo(String no) {
        this.no = no;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public int getCount() {
        return count;
    }

    public void setCount(int count) {
        this.count = count;
    }

    @Override
    public int compareTo(Classroom o) {
        return this.no.compareTo(o.getNo());
    }

    public static void main(String[] args) {
        // 创建TreeSet对象
        TreeSet<Classroom> set = new TreeSet<>();
        // 添加教室对象
        set.add(new Classroom("101", "A栋", 50));
        set.add(new Classroom("104", "A栋", 100));
        set.add(new Classroom("102", "B栋", 80));
        set.add(new Classroom("103", "C栋", 60));
        // 遍历TreeSet
        for (Classroom classroom : set) {
            System.out.println(classroom.getNo() + " " + classroom.getAddress() + " " + classroom.getCount());
        }
    }
}

输出结果为：

101 A栋 50
102 B栋 80
103 C栋 60
104 A栋 100

可以看到，教室对象按照教室号从小到大排序。遍历TreeSet时，可以直接使用foreach循环。