java - java中如何对具有不同属性的列表进行排序

Question

我想要对包含属性名称和类(class)的学生对象列表进行排序，以便根据名称进行排序，如果两个名称相同，那么它应该考虑类(class)进行排序...我可以单独进行，但想要一个列出...请帮忙...

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package studentlist;

import java.util.*;

/**
 *
 * @author Administrator
 */
public class StudentList {

    /**
     * @param args the command line arguments
     */
    String name, course;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getCourse() {
        return course;
    }

    public void setCourse(String course) {
        this.course = course;
    }

    public StudentList(String name, String course) {
        this.name = name;
        this.course = course;
    }

    public static void main(String[] args) {
        // TODO code application logic here
        List<StudentList> list = new ArrayList<StudentList>();

        list.add(new StudentList("Shaggy", "mca"));
        list.add(new StudentList("Roger", "mba"));
        list.add(new StudentList("Roger", "bba"));
        list.add(new StudentList("Tommy", "ca"));
        list.add(new StudentList("Tammy", "bca"));

        Collections.sort(list, new NameComparator());
        Iterator ir = list.iterator();

        while (ir.hasNext()) {
            StudentList s = (StudentList) ir.next();
            System.out.println(s.name + " " + s.course);
        }

        System.out.println("\n\n\n ");
        Collections.sort(list, new CourseComparator());
        Iterator ir1 = list.iterator();

        while (ir1.hasNext()) {
            StudentList s = (StudentList) ir1.next();
            System.out.println(s.name + " " + s.course);
        }

    }

}

class NameComparator implements Comparator<StudentList> {

    public int compare(StudentList s1, StudentList s2) {

        return s1.name.compareTo(s2.name);

    }

}

class CourseComparator implements Comparator<StudentList> {

    public int compare(StudentList s1, StudentList s2) {
        return s1.course.compareTo(s2.course);
    }
}

Answer 1

您只需将两个比较放在一个比较器中即可。

• 首先测试name是否相等:
  • 如果不相等，则返回name的比较结果。
  • 如果相等，则继续比较类(class):

以下比较器可以工作:

class NameCourseComparator implements Comparator<StudentList> {

    public int compare(StudentList s1, StudentList s2) {
        if (s1.name.equals(s2.name)) {
            return s1.course.compareTo(s2.course);
        }
        return s1.name.compareTo(s2.name);
    }
}