how can you sort 2 dimensional String array?

Question

How can you sort this

String  [][] Array11= {{array[i]},{array2[i]},{array3[i]}};

brief explanation about what im trying to work: array contains student ID number array2 contains student name array3 contains student course. All of them are STRING ARRAYS

if i input:

1:

ID number: 5 name: A course: CS

2:

ID number: 3 Name: B course: IT

i should sort it by its ID number so the output would look like this

ID Number Name Course 3 B IT 5 A CS

or if you have any other suggestions on how to make it work, please help me. :)

Answer 1

You should replace your 2D string array with a 1D array of Student s, where you create a Student class that has the attributes "id", "name", and "course".

Then you create a class that implements Comparator<Student> , say StudentComparator . Its compare method should return a negative number, 0 , or a positive number, depending on whether the first Student compares to the second Student as less than, equal to, or greater than.

Answer 2

You need to create a custom Comparator .

Check out Column Comparator it provides two approaches:

1. create a custom Comparator to sort the Array by a given index
2. use the ColumnComparator as a reusuable Comparator simply by specify the index of the column to sort on.

Or a better design is to create a custom Student Object to store the properties of the Student (Id, Name, Course), then you can use the Bean Comparator , to sort on any of the properties in the class.

Answer 3

The way you are storing the data is not appropriate. I would recommend you to define a class for your Students that implements Comparable. Then overide compareTo() function such that it compares by the course id

 public class Student implements Comparable<Student >
 {
  public  int id;
  public  String name;
  public  String course;

  public int compareTo(Student s)
  {
     if(s ==null)
       return 1;

    return id - s.id;
  }

 }

Now you can store all your students in the ArrayList as follows :

Student [] studentsList = new Student [sizeOfStudent];

Now you can just sort using Arrays utility sort method :

Arrays.sort(studentsList);

Note: If you want to use a different data structure, then I would recommend using ArrayList instead of an Array.

Answer 4

The best way to do this is to stop pretending that you are using C and start actually using Java.

step 1: create an object that contains student id, student name, and student course.

step 2: store these objects in a collection (array, list, other) that makes sense.

step 3; sort the collections.

here is some code:

public class StudentBlam implements Comparable<StudentBlam>
{
    private final String course;
    private final String id;
    private final String name;

    public StudentBlam(
        final String course,
        final String id,
        final String name)
    {
        this.course = course;
        this.id = id;
        this.name = name;
    }

    @Override
    public int compareTo(final StudentBlam other)
    {
        return id.compareTo(other.getId());
    }

    public String getCourse()
    {
        return course;
    }

    public String getId()
    {
        return id;
    }

    public String getName()
    {
        return name;
    }
}