定制对ArrayList的sort方法的自定义排序

java中的ArrayList需要通过collections类的sort方法来进行排序

如果想自定义排序方式则需要有类来实现Comparator接口并重写compare方法

调用sort方法时将ArrayList对象与实现Commparator接口的类的对象作为参数

示例:

// 外部类的方式

import java.util.ArrayList; import java.util.Collections;

import java.util.Comparator; import java.util.List;

public class Test {  public static void main(String[] args) {

Student zlj = new Student("丁晓宇", 21);

Student dxy = new Student("赵四", 22);

Student cjc = new Student("张三", 11);

Student lgc = new Student("刘武", 19);

List<Student> studentList = new ArrayList<Student>();

studentList.add(zlj);

studentList.add(dxy);

studentList.add(cjc);

studentList.add(lgc);

Collections.sort(studentList, new SortByAge());

for (Student student : studentList) {

System.out.println(student.getName() + " / " + student.getAge());

}

System.out.println("  =  ");

Collections.sort(studentList, new SortByName());

for (Student student : studentList) {

System.out.println(student.getName() + " / " + student.getAge());

}  } }

class SortByAge implements Comparator {

public int compare(Object o1, Object o2) {

Student s1 = (Student) o1;   Student s2 = (Student) o2;

if (s1.getAge() > s2.getAge())    return 1;   return 0;  } }

class SortByName implements Comparator {

public int compare(Object o1, Object o2) {

Student s1 = (Student) o1;

Student s2 = (Student) o2;

return s1.getName().compareTo(s2.getName());  } }

//匿名内部类的方式

//按照受益人级别进行排序

Collections.sort(beneficiarys,new Comparator(){

@Override

public int compare(Object o1, Object o2) {

Beneficiary s1 = (Beneficiary) o1;

Beneficiary s2 = (Beneficiary) o2;

if (Integer.parseInt(s1.getBeneficiaryOrder()) > Integer.parseInt(s2.getBeneficiaryOrder()))

return 1;

return 0;

}    });