Android List(集合)中的对象以某一个字段排序

在Android开发中，有时我们需要对一个对象的集合按照某一个字段进行排序，

• Bean

public class Student {
private int studentId;
private String studentName;
private int age;
public Student(int studentId , String studentName, int age){
this.studentId=studentId;
this.studentName=studentName;
this.age=age;
    }
public int getStudentId() {
return studentId;
    }
public void setStudentId(int studentId) {
this.studentId = studentId;
    }
public String getStudentName() {
return studentName;
    }
public void setStudentName(String studentName) {
this.studentName = studentName;
    }
public int getAge() {
return age;
    }
public void setAge(int age) {
this.age = age;
    }

}

• 实现排序

  实现排序比较类 Comparator ，里面实现排序规则。

public class test {

/**
 * @param args
 */
public static void main(String[] args) {
         Student stu1 = new Student (1,"zhangsan",28);
         Student stu2 = new Student (2,"zhagnsan",19);
         Student stu3 = new Student (3,"wangwu",19);
         Student stu4 = new Student (4,"wangwu",19);
         Student stu5 = new Student (5,"zhaoliu",18);

          ArrayList<Student> list = new ArrayList<Student>();
          list.add(stu1);
          list.add(stu2);
          list.add(stu3);
          list.add(stu4);
          list.add(stu5); 
//排序规则，这里是以年龄先排序，如果年龄相同
        Comparator<Student> comparator = new Comparator<Student>() {
public int compare(Student s1, Student s2) {
// 先排年龄
if (s1.getAge() != s2.getAge()) {
return s1.getAge() - s2.getAge();
                } else if (!s1.getStudentName().equals(s2.getStudentName())) {
// 年龄相同则按姓名排序
return s1.getStudentName().compareTo(s2.getStudentName());
                } else {
// 姓名也相同则按学号排序
return s1.getStudentId() - s2.getStudentId();
                }
            }
        };

//这里就会自动根据规则进行排序
          Collections.sort(list,comparator);
for(int i=0;i<list.size();i++){
              Student stu=list.get(i);
              System.out.println("年龄:"+stu.getAge()+" 姓名:"+stu.getStudentName()+" 学号:"+stu.getStudentId());
          }

    }

}

排序结果

结果：
年龄:18   姓名:zhaoliu   学号:5
年龄:19   姓名:wangwu   学号:3
年龄:19   姓名:wangwu   学号:4
年龄:19   姓名:zhagnsan   学号:2
年龄:28   姓名:zhangsan   学号:1

也可以想下面这样写：

    Collections.sort(list, new Comparator<GoodsBean>() {
            @Override
            public int compare(GoodsBean bean1, GoodsBean bean2) {

                if (Integer.valueOf(bean1.getScore()).compareTo(Integer.valueOf(bean2.getScore())) == 0) {
                    return Integer.valueOf(bean1.getRecommend_num()).compareTo(Integer.valueOf(bean2.getRecommend_num()));
                } else {
                    return Integer.valueOf(bean1.getScore()).compareTo(Integer.valueOf(bean2.getScore()));
                }
            }
        });

这样就可以对一个集合中的数据各种排序了。