Best practices for catching Throwable in Java

Question

Sometimes, you just have to catch Throwable, e.g. when writing a dispatcher queue that dispatches generic items and needs to recover from any errors (said dispatcher logs all caught exceptions, but silently, and then execution is continued on other items).

One best practice I can think of is to always rethrow the exception if it's InterruptedException, because this means someone interrupted my thread and wants to kill it.

Another suggestion (that came from a comment, not an answer) is to always rethrow ThreadDeath

Any other best practices?

Answer 1

Probably the most important one is, never swallow a checked exception. By this I mean don't do this:

try {
  ...
} catch (IOException e) {
}

unless that's what you intend. Sometimes people swallow checked exceptions because they don't know what to do with them or don't want to (or can't) pollute their interface with "throws Exception" clauses.

If you don't know what to do with it, do this:

try {
  ...
} catch (IOException e) {
  throw new RuntimeException(e);
}

The other one that springs to mind is to make sure you deal with exceptions. Reading a file should look something like this:

FileInputStream in = null;
try {
  in = new FileInputStream(new File("..."));;
  // do stuff
} catch (IOException e) {
  // deal with it appropriately
} finally {
  if (in != null) try { in.close(); } catch (IOException e) { /* swallow this one */ }
}