Finding the longest common prefix.

Here’s an example Java program that finds the longest common prefix among an array of strings:

    public class LongestCommonPrefix {

    public static String findLongestCommonPrefix(String[] strs) {

        if (strs == null || strs.length == 0) {

            return "";

        }

        // Start with the first string as the initial common prefix

        String prefix = strs[0];

        // Iterate through the remaining strings

        for (int i = 1; i < strs.length; i++) {

            // Update the common prefix by comparing characters

            while (strs[i].indexOf(prefix) != 0) {

                prefix = prefix.substring(0, prefix.length() - 1);

            }

            // If the prefix becomes empty, there is no common prefix

            if (prefix.isEmpty()) {

                return "";

            }

        }

        return prefix;

    }

    public static void main(String[] args) {

        String[] strings = {"flower", "flow", "flight"};

        String longestCommonPrefix = findLongestCommonPrefix(strings);

        System.out.println("Longest common prefix: " + longestCommonPrefix);

    }

}

In this example, the `findLongestCommonPrefix` method takes an array of strings as input and returns the longest common prefix as a string. It starts by initializing the `prefix` variable with the first string in the array. Then, it iterates through the remaining strings, updating the `prefix` by comparing characters. If the prefix becomes empty at any point, it means there is no common prefix, and an empty string is returned. Finally, in the `main` method, we provide an example array of strings and print the longest common prefix. In this case, the output will be:

Longest common prefix: fl

This indicates that the longest common prefix among the strings “flower”, “flow”, and “flight” is “fl”.