import java.util.Iterator;
import java.util.*;public class TreeSetTest {public static void main(String[] args) {Set ts = new TreeSet();ts.add("abc");ts.add("xyz");ts.add("rst");Iterator it = ts.iterator();while (it.hasNext()) {System.out.println(it.next());}}
}

package test.treeset;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;public class test_treeset {@SuppressWarnings("unchecked")public static void main(String[] args) {Set ts = new TreeSet();ts.add(new Teacher("zhangsan", 1));ts.add(new Teacher("lisi", 2));ts.add(new Teacher("wangmazi", 3));ts.add(new Teacher("wangwu",4));ts.add(new Teacher("mazi", 3));Iterator it = ts.iterator();while (it.hasNext()) {System.out.println(it.next());}}
}
class Teacher implements Comparable {int num;String name;Teacher(String name, int num) {this.num = num;this.name = name;}public String toString() {return "学号：" + num + "\t\t姓名：" + name;}//o中存放时的红黑二叉树中的节点，从根节点开始比较public int compareTo(Object o) {Teacher ss = (Teacher) o;int result = num < ss.num ? 1 : (num == ss.num ? 0 : -1);//降序//int result = num > ss.num ? 1 : (num == ss.num ? 0 : -1);//升序if (result == 0) {result = name.compareTo(ss.name);}return result;}
}

  public TreeSet(Comparator<? super E> comparator) {this(new TreeMap<E,Object>(comparator));}

package test.treeset;import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;public class TreeSetTest {@SuppressWarnings("unchecked")public static void main(String[] args) {TreeSet ts = new TreeSet(new Teacher2.TeacherCompare());ts.add(new Teacher2("zhangsan", 2));ts.add(new Teacher2("lisi", 1));ts.add(new Teacher2("wangmazi", 3));ts.add(new Teacher2("mazi", 3));Iterator it = ts.iterator();while (it.hasNext()) {System.out.println(it.next());}}
}class Teacher2 {int num;String name;Teacher2(String name, int num) {this.num = num;this.name = name;}public String toString() {return "学号：" + num + "    姓名：" + name;}static class TeacherCompare implements Comparator {// 老师自带的一个比较器//o1中存放的事目标节点//o2中存放时的红黑二叉树中的节点，从根节点开始比较public int compare(Object o1, Object o2) {Teacher2 s1 = (Teacher2) o1;// 转型Teacher2 s2 = (Teacher2) o2;// 转型int result = s1.num > s2.num ? 1 : (s1.num == s2.num ? 0 : -1);if (result == 0) {result = s1.name.compareTo(s2.name);}return result;}}}