How can I sort an ArrayList of Strings in Java?

Question

I have Strings that are put into an ArrayList randomly.

private ArrayList<String> teamsName = new ArrayList<String>();
String[] helper;

For example:

teamsName.add(helper[0]) where helper[0] = "dragon";   
teamsName.add(helper[1]) where helper[1] = "zebra";   
teamsName.add(helper[2]) where helper[2] = "tigers" // and so forth up to about 150 strings.

Given the fact that you cannot control the inputs (i.e. string that is coming into the ArrayList is random; zebra or dragon in any order), once the ArrayListis filled with inputs, how do I sort them alphabetically excluding the first one?

teamsName[0] is fine; sort teamsName[1 to teamsName.size] alphabetically.

and btw why is first element excluded ? I hope it's not because first element is the header element like 'Team name'... that should be managed in frontend only, and filtered later... — Andrea Ligios
– Andrea Ligios, Commented Oct 24, 2012 at 9:41
first element is the name of my team so I would like to have that as first; it will be on the drop down menu so like how we have United States as the first and alphabetize the rest of the countries — antz
– antz, Commented Oct 24, 2012 at 9:42

Juvanis · Accepted Answer · 2012-10-24 09:40:23Z

44

Collections.sort(teamsName.subList(1, teamsName.size()));

The code above will reflect the actual sublist of your original list sorted.

answered Oct 24, 2012 at 9:40

Juvanis

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4 Comments

Jean Logeart Over a year ago

You need to delcare the sublist outside the sort to get the results: List<String> sublist = teamsName.subList(1, teamsName.size()); Collections.sort(sublist);

dokaspar Over a year ago

Shouldn't the fromIndex in the subList be a 0 instead of a 1?

rayryeng Over a year ago

@dokaspar No. The OP expressly wants to exclude the first element. Read the question - specifically at the end.

Hayra Over a year ago

OP's request can create some misunderstanding when copying and pasting.. As question looks more generic...

Rohit Jain · Accepted Answer · 2012-10-24 09:46:35Z

12

Check Collections#sort method. This automatically sorts your list according to natural ordering. You can apply this method on each sublist you obtain using List#subList method.

private List<String> teamsName = new ArrayList<String>();
List<String> subList = teamsName.subList(1, teamsName.size());
Collections.sort(subList);

edited Oct 24, 2012 at 9:46

answered Oct 24, 2012 at 9:40

Rohit Jain

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Comments

npinti · Accepted Answer · 2012-10-24 09:39:43Z

6

Take a look at the Collections.sort(List<T> list).

You can simply remove the first element, sort the list and then add it back again.

answered Oct 24, 2012 at 9:39

npinti

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Comments

petrsyn · Accepted Answer · 2012-10-24 09:58:30Z

5

You might sort the helper[] array directly:

java.util.Arrays.sort(helper, 1, helper.length);

Sorts the array from index 1 to the end. Leaves the first item at index 0 untouched.

See Arrays.sort(Object[] a, int fromIndex, int toIndex)

edited Oct 24, 2012 at 9:58

answered Oct 24, 2012 at 9:41

petrsyn

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Mario Kutlev · Accepted Answer · 2013-09-25 14:52:35Z

3

You can use TreeSet that automatically order list values:

import java.util.Iterator;
import java.util.TreeSet;

public class TreeSetExample {

    public static void main(String[] args) {
        System.out.println("Tree Set Example!\n");

        TreeSet <String>tree = new TreeSet<String>();
        tree.add("aaa");
        tree.add("acbbb");
        tree.add("aab");
        tree.add("c");
        tree.add("a");

        Iterator iterator;
        iterator = tree.iterator();

        System.out.print("Tree set data: ");

        //Displaying the Tree set data
        while (iterator.hasNext()){
            System.out.print(iterator.next() + " ");
        }
    }

}

I lastly add 'a' but last element must be 'c'.

edited Sep 25, 2013 at 14:52

Mario Kutlev

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answered Oct 24, 2012 at 9:57

katsu

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1 Comment

bronzenose Over a year ago

TreeSet is definitely handy but a set is not a list. Using TreeSet will remove duplicates which may be unwanted: the question is about sorting, not sorting and de-duping.

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