Question

I have a simple servlet where I write to a file if it has a queryparameter ‘hello’, and since this is a test I want to display the error the the webpage also.

IntelliJ is complaining that I am not catching the IOException, not sure what’s wrong:

private static void WriteToFile(String filePath, String fileName, String fileData) {

    FileWriter writer = null;

    try {
        writer = new FileWriter(fileName);
        writer.write(fileData);
    } catch(IOException ex) {


    } finally {
        if(writer != null) {
            writer.close();
        }

    }


}

Also, in my exception, I noticed on the web most people write:

How can I output the error to the web page?

Answer 1

You’re not catching IOException when you call writer.close(); in the finally block.

You’re also completely swallowing any IOException thrown in the main code, which is a really bad idea. If something’s goes wrong, you’ll have no idea what’s happening.

I would personally suggest that you let that method throw the exception to the caller:

private static void writeToFile(String filePath, String fileName,
                                String fileData) throws IOException {
  FileWriter writer = new FileWriter(fileName);
  try {    
    writer.write(fileData);
  } finally {
    writer.close();
  }
}

Note that if the try block throws an exception and the finally block does, you’ll effectively “lose” the original exception. You may want to suppress exceptions throw when closing.

Or just use Guava which makes all of this simpler anyway with its Files class.

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

(I note that you’re ignoring filePath by the way – why?)