Matching Characters from a Control String to Array Words

Filtering and Grouping Array Elements Based on String Matching

Java-based solution using nested loops and modular functions

public class Main {
    public static void main(String[] args) {
        String[] array = {"reference", "class", "method", "type", "constructor", "recursive"};
        String keyWord = "structure";
        print(array, keyWord);
    }

    // Function to filter and print matching results
    static void print(String[] array, String keyWord) {
        String filteredKeyWord = removeDuplicates(keyWord.toLowerCase());
        for (char c : filteredKeyWord.toCharArray()) {
            StringBuilder matches = new StringBuilder();
            for (String word : array) {
                if (word.charAt(0) == c) {
                    if (matches.length() > 0) {
                        matches.append(", ");
                    }
                    matches.append(word);
                }
            }
            if (matches.length() > 0) {
                System.out.println(c + ": " + matches);
            }
        }
    }

    // Helper function to remove duplicate characters from a string
    static String removeDuplicates(String str) {
        StringBuilder result = new StringBuilder();
        for (char c : str.toCharArray()) {
            if (result.indexOf(String.valueOf(c)) == -1) {
                result.append(c);
            }
        }
        return result.toString();
    }
}

Optimized Solution Using Streams in Java

Java 8+ solution leveraging streams for readability and performance

import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) {
        String[] array = {"reference", "class", "method", "type", "constructor", "recursive"};
        String keyWord = "structure";
        printWithStreams(array, keyWord);
    }

    static void printWithStreams(String[] array, String keyWord) {
        String filteredKeyWord = keyWord.toLowerCase().chars()
                .distinct()
                .mapToObj(c -> (char) c)
                .map(String::valueOf)
                .collect(Collectors.joining());

        for (char c : filteredKeyWord.toCharArray()) {
            String matches = Arrays.stream(array)
                    .filter(word -> word.startsWith(String.valueOf(c)))
                    .collect(Collectors.joining(", "));

            if (!matches.isEmpty()) {
                System.out.println(c + ": " + matches);
            }
        }
    }
}

Unit Test for Both Solutions

JUnit-based test to validate outputs in different scenarios

import org.junit.jupiter.api.Test;
import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import static org.junit.jupiter.api.Assertions.assertEquals;

public class MainTest {
    @Test
    void testPrint() {
        String[] array = {"reference", "class", "method", "type", "constructor", "recursive"};
        String keyWord = "structure";
        ByteArrayOutputStream outContent = new ByteArrayOutputStream();
        System.setOut(new PrintStream(outContent));

        Main.print(array, keyWord);
        String expectedOutput = "t: type\nr: reference, recursive\nc: class, constructor\n";
        assertEquals(expectedOutput, outContent.toString());
    }

    @Test
    void testPrintWithStreams() {
        String[] array = {"reference", "class", "method", "type", "constructor", "recursive"};
        String keyWord = "structure";
        ByteArrayOutputStream outContent = new ByteArrayOutputStream();
        System.setOut(new PrintStream(outContent));

        Main.printWithStreams(array, keyWord);
        String expectedOutput = "t: type\nr: reference, recursive\nc: class, constructor\n";
        assertEquals(expectedOutput, outContent.toString());
    }
}

Commonly Asked Questions about String Matching and Nested Loops

1. What is the purpose of the toCharArray() method?
2. The toCharArray() method converts a string into a character array, enabling iteration over each character for processing.
3. How does the removeDuplicates() function work?
4. The removeDuplicates() function builds a new string by appending only unique characters from the input string, ensuring no repeated processing.
5. Why is startsWith() preferred over manually checking characters?
6. startsWith() simplifies the code by directly verifying if a string begins with a specified prefix, making it less error-prone.
7. Can streams handle large datasets efficiently?
8. Yes, Java streams, especially with parallelStream(), can process large datasets efficiently by leveraging parallel computation.
9. What is the advantage of using Collectors.joining() for output?
10. Collectors.joining() aggregates elements from a stream into a single string with optional delimiters, enhancing readability and output formatting.
11. How can unit tests improve reliability?
12. Unit tests ensure each function, like print(), performs correctly under various scenarios, reducing bugs in production.
13. How does hash-based searching improve performance?
14. By pre-indexing data into a hash map, matches can be found in constant time, making the process faster for large arrays.
15. What is locale-sensitive string comparison?
16. It ensures accurate comparisons for strings in different languages or encodings using tools like Java’s Collator.
17. Can this script be integrated with front-end applications?
18. Yes, the logic can be adapted for use in JavaScript or frameworks like React to create interactive and dynamic outputs.
19. What is the benefit of modularizing the code?
20. Breaking the code into reusable methods like removeDuplicates() and matchFirstWithLetter() makes it easier to maintain and expand.

Final Thoughts on Efficient String Matching

In solving the problem of matching control string characters with array words, key techniques like deduplication and grouping were highlighted. These ensure accurate results and efficient handling of large datasets. Such solutions are essential for real-world applications, such as search engines or data categorization.

Modular programming approaches, demonstrated through reusable methods, allow for easier maintenance and scalability. Whether applied to small projects or large-scale systems, these concepts remain fundamental. By leveraging Java’s powerful commands, developers can solve similar string matching challenges effectively and innovatively. 🧩