CODEWITHSUNDEEP
javaarrays
Kurtiss
Kurtiss

Reputation: 525

How to sort an array by a specific data segment?

I have an array of Strings like so:

String[] array = { "CC/2", "DDD/3", "AAAA/4", "B/1" };
Arrays.sort(array);
System.out.println(Arrays.toString(array));

When I execute this code, I get the following:

[AAAA/4, B/1, CC/2, DDD/3]

This is correct, however I want to sort it by the numbered value instead, so that I get the following result:

[B/1, CC/2, DDD/3, AAAA/4]

How do I go about doing this?

Upvotes: 3

Views: 294

Answers (5)

Zoltán
Zoltán

Reputation: 22206

Use a custom Comparator and remove the characters before the numbers, like this:

Arrays.sort(array, new Comparator<String>() {
    @Override
    public int compare(String o1, String o2) {
        return o1.replaceAll("[A-Z]+/", "").compareTo(o2.replaceAll("[A-Z]+/", ""));
    }
});

The .replaceAll("[A-Z]+/", "") part removes your leading CC/, AAAA/, and so on; assuming your strings always start with at least one uppercase letter followed by a slash (/).

Upvotes: 2

Akash Thakare
Akash Thakare

Reputation: 23012

You can do it like this by the use of Comparator<String>

    /* You may found some shortcuts for this
       but following code is easy to understand 
    */
    String[] array = { "CC/2", "DDD/3", "AAAA/4", "B/1"};
    Arrays.sort(array, new Comparator<String>() {

        public int compare(String o1, String o2) {
            int i1,i2;
            /* 
               You should add some checks like 
               1] null check
               or 
               2] whether String contains / or not etc before going for further 
               code.
            */
            /* Get Numbers from String To compare */
            i1=Integer.valueOf(o1.split("/")[1]);
            i2=Integer.valueOf(o2.split("/")[1]);
            //May throw NumberFormatException so be careful with this

            if(i1>i2)
                return 1;
            else if(i1<i2)
                return -1;
            else
                return 0;
        }
    });
    System.out.println(Arrays.toString(array));//Print array

Upvotes: 4

Buzz
Buzz

Reputation: 1907

You will have to make your own sorting function. If the numbers will always be at the end of the strings you could reverse the strings using

StringBuilder().reverse().toString()

then you could sort them like you did before and then reverse them back. This will give you give you the strings in order of the numbers, but if you have multiple strings with the same number they will be sorted backwards.

Upvotes: 0

QBrute
QBrute

Reputation: 4541

You need a custom Comparator:

Comparator<String> c = new Comparator<String>() {
    @Override
    public int compare(String s1, String s2) {
        return s1.split("/")[1].compareTo(s2.split("/")[1]);
    }
};
String[] array = { "CC/2", "DDD/3", "AAAA/4", "B/1" };
Arrays.sort(array, c);
System.out.println(Arrays.toString(array));

This prints [B/1, CC/2, DDD/3, AAAA/4]

Upvotes: 2

Julian
Julian

Reputation: 21

Have a look at sort(T[] a, Comparator c) in Arrays class: http://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html

A custom comparator may be what you want

Upvotes: 0

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