Sort array via item's sub-strings

Question

My array contains items set out like:

"item_name_1::item_description::item_value"

(so each item in the array contains separate pieces of data which is later split at "::")

and my question is, how can i sort the array by the "ITEM_VALUE" (which is a numeric value), i have tried the following, with no luck:

Arrays.sort(inputArr, new Comparator<String>() {
    @Override
    public int compare(String entry1, String entry2) {
        String[] entry1Split = entry1.split("::");
        String[] entry2Split = entry2.split("::");

        return entry1Split[2].compareTo(entry2Split[2]);
    }
});

What is the problem with the code you've posted? It seems to be OK. — bpgergo
– bpgergo, Commented Sep 5, 2011 at 11:59
From perfromance perspective it worst splitting item each time you are doing comparision, split original array items in temporary arrays and then do sort — sll
– sll, Commented Sep 5, 2011 at 12:00

Aleks G · Accepted Answer · 2011-09-05 11:59:31Z

2

You should be able to do this:

Arrays.sort(inputArr, new Comparator<String>() {
    @Override
    public int compare(String entry1, String entry2) {
        String[] entry1Split = entry1.split("::");
        String[] entry2Split = entry2.split("::");

        return Double.valueOf(entry1Split[2]).compareTo(Double.valueOf(entry2Split[2]));
    }
});

that is, if your numerical values are floating point values. If they are integer, you can use Integer.valueOf instead of Double.valueOf.

answered Sep 5, 2011 at 11:59

Aleks G

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pillingworth · Accepted Answer · 2011-09-05 12:01:37Z

1

You may want to think about parsing the strings in the array and creating an object for each entry - something like

class Item {

    String value;
    String description
    Integer value;
}

that way you'll only parse the string once per object and not multiple times each time the sort algorithm needs to to do a compare.

answered Sep 5, 2011 at 12:01

pillingworth

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3 Comments

Aleks G Over a year ago

While a useful comment in itself, it does not answer his question, therefore it should be a comment, not an answer.

Sebastian Nowak Over a year ago

There's no way to post multiline answers and sample codes in the comment.

pillingworth Over a year ago

The downside of a real time dynamic system - Aleks G answered the question whilst I was part way through typing my answer. There didn't seem to be any point in repeating the answer so I edited the repeated stuff and was left with what should arguably have been a comment.

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