Finding line number of a word in a text file using java

Question

I require searching a word in a text file and display the line number using java. If it appears more than once I need to show all the line numbers in the output. Can anyone

Answer 1

Read the text file using Java class LineNumberReader and call method getLineNumber to find the current line number.

http://docs.oracle.com/javase/7/docs/api/java/io/LineNumberReader.html

Answer 2

You can store this information manually. Whenever you are invoking readline() of your BufferedReader, if you're using such, you can also increment a counter by one. E.g.,

public int grepLineNumber(String file, String word) throws Exception {
    BufferedReader buf = new BufferedReader(new InputStreamReader(new DataInputStream(new FileInputStream(file))));

    String line;
    int lineNumber = 0;
    while ((line = buf.readLine()) != null)   {
        lineNumber++;
        if (word.equals(line)) {
            return lineNumber;
        }
    }
    return -1;
}

Answer 3

Something like this might work:

public ArrayList<Integer> find(String word, File text) throws IOException {
    LineNumberReader rdr = new LineNumberReader(new FileReader(text));
    ArrayList<Integer> results = new ArrayList<Integer>();
    try {
        String line = rdr.readLine();
        if (line.indexOf(word) >= 0) {
            results.add(rdr.getLineNumber());
        }
    } finally {
        rdr.close();
    }
    return results;
}