Question

Say I have the following function

public static void myfunc(String filename) {
    new FileInputStream(filename);
}

When I call that function, will there be resource leak because the FileInputStream is never released?

And future reference, is there a way I could verify that the resource hasn’t been released after the function has been called?

Answer 1

Yes, there is a resource leak. Most IDEs (such as Eclipse) will issue a warning indicating this. You should probably do something like along the lines of:

public static void myfunc(String filename) throws IOException {
    FileInputStream stream = null;
    try {
        stream = new FileInputStream(filename);
        ...
    } finally {
        stream.close();
    }
}

Or, if you’re using Java 7, you could use the try-with-resource statement.