How can I get the line number where the word has been found?

Question

private static List<A> compute(Path textFile, String word) {
    List<A> results = new ArrayList<A>();

    try {
        Files.lines(textFile).forEach(line -> {

            BreakIterator it = BreakIterator.getWordInstance();
            it.setText(line.toString());

            int start = it.first();
            int end = it.next();

            while (end != BreakIterator.DONE) {
                String currentWord = line.toString().substring(start, end);
                if (Character.isLetterOrDigit(currentWord.charAt(0))) {
                    if (currentWord.equals(word)) {
                        results.add(new WordLocation(textFile, line));
                        break;
                    }
                }
                start = end;
                end = it.next();
            }
        });

    } catch (IOException e) {
        e.printStackTrace();
    }
    return results;
}

How can I get the line number which the word has been found? I want to use a stream to calculate in Lamdba. Do you have any idea?

Answer 1

public class Try {

    public static void main(String[] args) {

        Path path = Paths.get("etc/demo.txt");
        List<String> result = compute(path, "Test");
        result.stream().forEach(s -> System.out.println(s));
    }

    private static List<String> compute(Path textFilePath, String wordToFind) {

        List<String> results = new ArrayList<String>();
        // Added position and initialized with 0
        int[] position = new int[]{0};
        try {
            Files.lines(textFilePath).forEach(line -> {

                BreakIterator it = BreakIterator.getWordInstance();
                it.setText(line.toString());

                int start = it.first();
                int end = it.next();
                // Increment position by 1 for each line
                position[0] += 1;

                while (end != BreakIterator.DONE) {
                    String currentWord = line.toString().substring(start, end);
                    if (Character.isLetterOrDigit(currentWord.charAt(0))) {
                        if (currentWord.equals(wordToFind)) {
                            results.add("File Path: " + textFilePath + ", Found Word: " + wordToFind + ", Line: " + position[0]);
                            break;
                        }
                    }
                    start = end;
                    end = it.next();
                }
            });

        } catch (IOException e) {
            e.printStackTrace();
        }
        return results;
    }

}

demo.txt:

Stream1
Review
Stream
2020-10-10 10:00
Test
0.0
admin HOST Test
Stream2
Review

Output:

Note:

1. This is an example for your reference as it uses List<String>.
2. Added int[] position = new int[]{0}; and position[0] += 1; for line numbers to be displayed.
3. In above example Test exists in line number 5 and 7.

Answer 2

You can use a LineNumberReader to get the linenumber. That would look something like this:

private static List<A> compute(Path textFile, String word) {
    List<A> results = new ArrayList<A>();

    try (final LineNumberReader reader = new LineNumberReader(new FileReader(textFile.toFile()))) {
        String line;
        while ((line = reader.readLine()) != null) {
            BreakIterator it = BreakIterator.getWordInstance();
            it.setText(line);

            int start = it.first();
            int end = it.next();

            final int lineNumber = reader.getLineNumber(); // here is your linenumber

            while (end != BreakIterator.DONE) {
                String currentWord = line.substring(start, end);
                if (Character.isLetterOrDigit(currentWord.charAt(0))) {
                    if (currentWord.equals(word)) {
                        results.add(new WordLocation(textFile, line));
                        break;
                    }
                }
                start = end;
                end = it.next();
            }
        }

    } catch (IOException e) {
        e.printStackTrace();
    }
    return results;
}