Java – the most effective idiom for reading only one integer from a file?

Trying to solve Facebook's Puzzle "happiness hop", http://www.facebook.com/careers/puzzles.php?puzzle_id=7 I only read an integer from a file I wonder if this is the most effective mechanism?

private static int readSoleInteger(String path) throws IOException {
    BufferedReader buffer = null;
    int integer = 0;

    try {
        String integerAsString = null;

        buffer = new BufferedReader(new FileReader(path));

        // Read the first line only.
        integerAsString = buffer.readLine();

        // Remove any surplus whitespace.
        integerAsString = integerAsString.trim();

        integer = Integer.parseInt(integerAsString);
    } finally {
        buffer.close();
    }

    return integer;
}

How do I create a Java string from the contents of a file?, But I don't know the efficiency of the idiom to answer this question

Looking at my code, it seems that many lines of code and objects are a trivial problem

Solution

The shortest way is to use scanner:

private static int readSoleInteger(String path) {
    Scanner s = new Scanner(new File(path));
    int ret = s.nextInt();
    s.close();
    return ret;
}

Please note that scanner swallows any ioexceptions, thus simplifying a lot of things

As for "most effective"... Well, the simple act of opening a file from disk may be the slowest part of any method you write for this In this case, don't worry too much about efficiency

Editor: I didn't realize that an integer can have spaces on both sides of it My code doesn't take this into account at present, but it's easy to make scanner skip things I have added this line

s.skip("\\s+");

Correct this

Edit 2: it doesn't matter. Scanner ignores spaces when trying to parse numbers: