sort 2d String array in java -sort index element inside my array

Question

Hi i need to sort array two Dimension in java but i need the sorting to be by index inside my array my array is

  String arr[][]={  {"joun","1525565","10"},
                           {"ALI","15256562","100"},
                           {"FATEH","1525534","20"}   };

I need to sort my array by index number two and the output is

   String arr[][]={ {"ALI","15256562","100"},
                       {"FATEH","1525534","20"},
                         {"joun","1525565","10"} };

my order must be 100 then 20 then 10

i tried to put this code in java put the problem the program get confused from the index 1 and two i used inside for loop Arrays.sort(arr[i])

possible duplicate of stackoverflow.com/questions/16846301/… — Sybren
– Sybren, Commented Apr 27, 2015 at 16:06
if it's work with Arrays.sort it will be better but i think it's not working with this method — badr aldeen
– badr aldeen, Commented Apr 27, 2015 at 16:09

Peter Lawrey · Accepted Answer · 2015-04-27 16:26:10Z

5

In Java 8 you would write this to sort by index 2 for decreasing numeric order with

Arrays.sort(arr, Comparator.comparing(row -> -Long.parseLong(row[2])));

or

Arrays.sort(arr, Comparator.comparing((String[] row) -> Long.parseLong(row[2]))
                           .reversed());

For ascending order as a String rather than a number.

Arrays.sort(arr, Comparator.comparing(row -> row[2]));

This would order 10, 100, 20 but if you made longer strings before shorter ones.

Arrays.sort(arr, Comparator.comparing((String[] row) -> row[2].length()).reversed()
                           .thenComparing(row->row[2]));

This would give the order as 100, 10, 20

BTW: I don't know why the first row needs the type given.

if you wanted to sort by number you could do

Arrays.sort(arr, Comparator.comparing(row -> Long.parseLong(row[2])));

This would put 10, 20, 100 in increasing order.

In Java 8 you can add an anonymous inner class to do the same thing.

edited Apr 27, 2015 at 16:26

answered Apr 27, 2015 at 16:07

Peter Lawrey

535k83 gold badges770 silver badges1.2k bronze badges

Sign up to request clarification or add additional context in comments.

12 Comments

badr aldeen Over a year ago

what is row here ? is it the array name ? because i get an error

Peter Lawrey Over a year ago

@user44444 are using using Java 8? row is the name of the nested array. What error do you get? This is using Java 8's lambdas and Streams API.

badr aldeen Over a year ago

ok i changed my project to 8 and there is no error but the code is not working with me i wrote Arrays.sort(arr, Comparator.comparing(row -> row[2])); for (String[] item : arr) { System.out.println(Arrays.toString(item)); } and i get the same last array

badr aldeen Over a year ago

the error is Type mismatch: cannot convert from String to Comparable<? super Comparable<? super U>>

Peter Lawrey Over a year ago

@user44444 I tried three different ways to sort the numbers. ;) can explain the sort order you want. Is it decreasing numeric order?

|

ioseb · Accepted Answer · 2015-04-27 16:19:46Z

1

Here is the solution with Comparator:

public class SortTest {
    public static void main(String[] args) {
        String arr[][]={  {"joun","1525565","10"},
                {"ALI","15256562","100"},
                {"FATEH","1525534","20"}   };

        Arrays.sort(arr, new Comparator<String[]>() {
            @Override
            public int compare(String[] o1, String[] o2) {
                return Integer.parseInt(o2[2]) - Integer.parseInt(o1[2]);
            }
        });

        for (String[] item : arr) {
            System.out.println(Arrays.toString(item));
        }
    }
}

edited Apr 27, 2015 at 16:19

answered Apr 27, 2015 at 16:07

ioseb

17k3 gold badges37 silver badges31 bronze badges

4 Comments

ioseb Over a year ago

@user44444 "it sort every thing" <- what do you mean?

badr aldeen Over a year ago

i mean it sort the number 1525565 and 10 my array now is {"joun","1525565","100"}, but now it's {"joun","1525565","10"} array[0] was {"joun","1525565","100"}

ioseb Over a year ago

@user44444 in your initial example it is: {"joun","1525565","10"} sorted output of my code is: [ALI, 15256562, 100] [FATEH, 1525534, 20] [joun, 1525565, 10] where is the issue?

badr aldeen Over a year ago

OK the problem was from me because my array is not the same what i wrote in the example but it similar i edit some thing in your code and it's working for me now your code is working immediately with my example above thanks :)

Collectives™ on Stack Overflow

sort 2d String array in java -sort index element inside my array

2 Answers 2

12 Comments

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

12 Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related