java - 如何在java中对具有不同属性的列表进行排序

Question

我想对包含属性名称和课程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，则应该考虑对课程进行排序......我可以单独进行但想要一个列表.. .PLz帮助...

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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Comparator中。

• 首先测试name是否相等：
  • 如果它们不相等，则返回 的比较结果name。
  • 如果它们相等，则移动以比较courses：

以下比较器将起作用：

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);
    }
}

Answer 2

一种简单的方法：

首先根据名称对列表进行排序。之后再次遍历列表。如果您按顺序找到任何相同的名称，请比较课程并相应地更新列表。

Answer 3

你可以稍微调整NameComparator一下

class NameComparator implements Comparator<StudentList> {
      public int compare(StudentList s1, StudentList s2) {
        if(s1.getName().equals(s2.getName()) {
           return s1.getCourse().compareToIgnoreCase(s2.getCourse());
        }else {
           return s1.getName().compareToIgnoreCase(s2.getName());   
      }
}