[Java] 纯文本查看 复制代码
public class Demo2_Genric {
/**
* 泛型固定下边界
* ? super E
*
* 泛型固定上边界
* ? extends E
*/
public static void main(String[] args) {
//demo1();
TreeSet<Student> ts1 = new TreeSet<>(new CompareByAge());
ts1.add(new Student("张三", 33));
ts1.add(new Student("李四", 13));
ts1.add(new Student("王五", 23));
ts1.add(new Student("赵六", 43));
TreeSet<BaseStudent> ts2 = new TreeSet<>(new CompareByAge());
ts2.add(new BaseStudent("张三", 33));
ts2.add(new BaseStudent("李四", 13));
ts2.add(new BaseStudent("王五", 23));
ts2.add(new BaseStudent("赵六", 43));
System.out.println(ts2);
}
public static void demo1() {
ArrayList<Student> list1 = new ArrayList<>();
list1.add(new Student("张三", 23));
list1.add(new Student("李四", 24));
ArrayList<BaseStudent> list2 = new ArrayList<>();
list2.add(new BaseStudent("王五", 25));
list2.add(new BaseStudent("赵六", 26));
list1.addAll(list2);
}
}
class CompareByAge implements Comparator<Student> {
@Override
public int compare(Student s1, Student s2) {
int num = s1.getAge() - s2.getAge();
return num == 0 ? s1.getName().compareTo(s2.getName()) : num;
}
}