How to Sort a 2D String Array by a Specific Column in Java?

Sorting a 2D String Array by a Specific Column

In Java, we can encounter situations where we need to organize data stored in a two-dimensional (2D) array. To accomplish this sorting effectively, we can utilize the Arrays.sort() method along with a custom comparator.

Consider the following example: We have a 2D array of strings where the first column represents a timestamp and the second column contains a message. Our goal is to sort the array based on the timestamps in ascending order.

To achieve this, we can define a class that implements the Comparator interface. This class will provide the logic for comparing elements in the array:

<code class="java">class TimestampComparator implements Comparator<String[]> {
    @Override
    public int compare(String[] entry1, String[] entry2) {
        return entry1[0].compareTo(entry2[0]);
    }
}</code>

In this comparator, we extract the timestamp values from each entry in the array and compare them using the String.compareTo() method.

With our comparator in place, we can now proceed with the sorting:

<code class="java">Arrays.sort(data, new TimestampComparator());</code>

Here, data represents the original 2D array.

After sorting, the data will be organized based on the timestamps in the first column. The resulting output will be:

2009.07.25 19:54 Message R
2009.07.25 20:01 Message F
2009.07.25 20:17 Message G
2009.07.25 20:24 Message A
2009.07.25 20:25 Message B
2009.07.25 20:30 Message D
2009.07.25 21:08 Message E

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