Question

Is this code

    BufferedWriter bw = new BufferedWriter(new FileWriter("test.txt"));
    try {
        bw.write("test");
    } finally {
        IOUtils.closeQuietly(bw);
    }

safe or not? As far as I understand when we close a BufferedWriter it will flush its buffer to the underlying stream and may fail due to an error. But IOUtils.closeQuietly API says that any exceptions will be ignored.

Is it possible a data loss will go unnoticed due to IOUtils.closeQuietly?

Answer 1

The code should look like this regarding to the javadoc of closeQuietly():

BufferedWriter bw = null;

try {
    bw = new BufferedWriter(new FileWriter("test.txt"));
    bw.write("test");
    bw.flush(); // you can omit this if you don't care about errors while flushing
    bw.close(); // you can omit this if you don't care about errors while closing
} catch (IOException e) {
    // error handling (e.g. on flushing)
} finally {
    IOUtils.closeQuietly(bw);
}

closeQuietly() is not intended for general use instead of calling close() directly on a Closable. Its intended use-case is for ensuring the close inside a finally-block – all error handling you need have to be done BEFORE that.

That means, if you want to react on Exceptions during the call of close() or flush() then you’ve to handle it the normal way. Adding closeQuietly() in your finally-block just ensures the close, e.g. when the flush failed and close was not called in try-block.