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());}elsereturn 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]