[英]how to sort a list with different attributes in java
我想对包含属性名称和课程的学生对象列表进行排序,以便基于名称进行排序,如果两个名称相同,则应考虑课程排序...我可以单独进行,但需要一个列表。 。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);
}
}
您只需要将两个比较放在单个Comparator中即可 。
name
是否相等:
name
的比较结果。 courses
: 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);
}
}
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。
您可以稍微调整一下NameComparator
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());
}
}
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