Question

Usually, when dealing with Java IO code, here is what I wrote

    FileOutputStream out = null;
    try
    {
        out = new FileOutputStream("myfile.txt");
        // More and more code goes here...
    }
    catch (Exception e)
    {
    }
    finally 
    {
        // I put the close code in finally block, to enture the opened
        // file stream is always closed even there is exception happened.
        if (out != null) {
            // Another try catch block, troublesome.
            try {
                out.close();
            } catch (IOException ex) {
            }
        }
    }

As you can see, while I try to close the file stream, I need to deal with another try…catch block.

Look troublesome 🙁

Is there any way I can avoid? I don’t feel comfortable in putting the close code in non-finally block, as exception caused by other codes will make no chance for “close” being called.

Answer 1

It is very important that you close streams in a finally. You can simplify this process with a utility method such as:

public static void closeStream(Closeable closeable) {
    if(null != closeable) {
      try {
        closeable.close();
      } catch(IOException ex) {
        LOG.warning("Failed to properly close closeable.", ex);
      }
    }
  }

I make it a point of at least logging a stream close failure. The usage then becomes:

FileOutputStream out = null;
try
{
    out = new FileOutputStream("myfile.txt");
    // More and more code goes here...
}
catch (Exception e)
{
}
finally 
{
    closeStream(out);
}

In Java 7 I believe that streams will be closed automatically and the need for such blocks should be mostly redundant.