How to Sort a Two-Dimensional Array by a Specific Date Column?

Sorting a Two-Dimensional Array by a Specific Column

Problem Overview

Given a two-dimensional array containing rows of data with two columns, where the first column represents a date in the "yyyy.MM.dd HH:mm" format and the second column is a String, we aim to sort the array based on the first column.

Solution using a Comparator

To sort the array, we can utilize the Arrays.sort() method along with a custom comparator. The comparator will compare the first elements of each row, which represent the dates.

<code class="java">import java.util.Arrays;
import java.util.Comparator;

public class ArraySorter {

    public static void main(String[] args) {
        // Input array
        String[][] data = {
                {"2009.07.25 20:24", "Message A"},
                {"2009.07.25 20:17", "Message G"},
                {"2009.07.25 20:25", "Message B"},
                {"2009.07.25 20:30", "Message D"},
                {"2009.07.25 20:01", "Message F"},
                {"2009.07.25 21:08", "Message E"},
                {"2009.07.25 19:54", "Message R"}
        };

        // Create a comparator to sort based on the first column (date)
        Comparator<String[]> comparator = Comparator.comparing(row -> row[0]);

        // Sort the array using the comparator
        Arrays.sort(data, comparator);

        // Print the sorted array
        for (String[] row : data) {
            System.out.println(row[0] + " " + row[1]);
        }
    }
}</code>

Output

The output will display the sorted data, with rows arranged in ascending order based on the first column (date):

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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