How to sort an List of object arrays in ascending order

Question

I have an hibernate entity class:

    @Entity
    @Table(name = "grade")
    @JsonIgnoreType
    public class StudentMaster implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "grade_id", unique = true, nullable = false)
    private Integer gradeId;

    @Column(name = "grade_name")
    private String gradeName;
    //getter and setter
   }

I have written a query that return a list of object array: String query = select T.gradeId, T.gradeName from grade where available = 1;

This return a list of object array

    List<Object[]> list = session.createQuery(query.toString()).list();

List is coming like

    [0]
     >[0] = 5001
     >[1] = "10"
    [1]
     >[0] = 5002
     >[1] = "11"
    [2]
     >[0] = 5003
     >[1] = "4"
    [3]
     >[0] = 5004
     >[1] = "18" 
      and so on....

I am trying to sort this in ascending order like 4, 10, 11, 18 I tried with the below code snippet but didn't work

   Collections.sort(list, new Comparator<StudentMaster>() {
        public int compare(StudentMaster s1, StudentMaster s2) {
            return s1.getGradeName().compareTo(s2.getGradeName());
        }
    });

can someone help me here. I am learning myself and new to coding so need help. Thank you

Answer 1

I would suggest to let DB to do its best and sort it for you. Just add order by to your query.

Update:

Since you want to order by integer value stored as string, you need to convert it to integer, using TO_NUMBER or specific SQL dialect syntax. In-memory sorting could be implemented like this:

new Comparator<Object[]>() {
 public int compare(Object[] o1, Object[] o2) {
 return Integer.valueOf((String) o1[1]).compareTo(Integer.valueOf((String) o2[1])); 
} 
});