In Java, is there any way to get (catch) all exceptions instead of catching the exceptions individually?
- 3and I will catch all those specific Exceptions with catch(Exception e){}??Johanna– Johanna2009-07-02 18:21:15 +00:00Commented Jul 2, 2009 at 18:21
- 1yeah. Since Exception is the base class of all exceptions, it will catch any exception.jjnguy– jjnguy2009-07-02 18:23:11 +00:00Commented Jul 2, 2009 at 18:23
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7 Answers
If you want, you can add throws clauses to your methods. Then you don't have to catch checked methods right away. That way, you can catch the exceptions later (perhaps at the same time as other exceptions).
The code looks like:
public void someMethode() throws SomeCheckedException { // code } Then later you can deal with the exceptions if you don't wanna deal with them in that method.
To catch all exceptions some block of code may throw you can do: (This will also catch Exceptions you wrote yourself)
try { // exceptional block of code ... // ... } catch (Exception e){ // Deal with e as you please. //e may be any type of exception at all. } The reason that works is because Exception is the base class for all exceptions. Thus any exception that may get thrown is an Exception (Uppercase 'E').
If you want to handle your own exceptions first simply add a catch block before the generic Exception one.
try{ }catch(MyOwnException me){ }catch(Exception e){ } 
Comments
While I agree it's not good style to catch a raw Exception, there are ways of handling exceptions which provide for superior logging, and the ability to handle the unexpected. Since you are in an exceptional state, you are probably more interested in getting good information than in response time, so instanceof performance shouldn't be a big hit.
try{ // IO code } catch (Exception e){ if(e instanceof IOException){ // handle this exception type } else if (e instanceof AnotherExceptionType){ //handle this one } else { // We didn't expect this one. What could it be? Let's log it, and let it bubble up the hierarchy. throw e; } } However, this doesn't take into consideration the fact that IO can also throw Errors. Errors are not Exceptions. Errors are a under a different inheritance hierarchy than Exceptions, though both share the base class Throwable. Since IO can throw Errors, you may want to go so far as to catch Throwable
try{ // IO code } catch (Throwable t){ if(t instanceof Exception){ if(t instanceof IOException){ // handle this exception type } else if (t instanceof AnotherExceptionType){ //handle this one } else { // We didn't expect this Exception. What could it be? Let's log it, and let it bubble up the hierarchy. } } else if (t instanceof Error){ if(t instanceof IOError){ // handle this Error } else if (t instanceof AnotherError){ //handle different Error } else { // We didn't expect this Error. What could it be? Let's log it, and let it bubble up the hierarchy. } } else { // This should never be reached, unless you have subclassed Throwable for your own purposes. throw t; } } 
6 Comments
codethulhu
I would argue that you should catch each exception explicitly, but the question explicitly asked how to catch everything a block of code would throw.
Anshul
That throwable was useful.
CubeJockey
This is the solution I was looking for, I needed an if else for exception handling. Thanks
cherryhitech
Throwable tip is really useful.
Datz
If you catch Throwables you should keep in mind that the VirtualMachineErrors such as StackOverflowError or OutOfMemoryError does not allow you to do much more than logging. They are outside of the applications control and you can not handle them.
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Catch the base exception 'Exception'
try { //some code } catch (Exception e) { //catches exception and all subclasses } 
7 Comments
George
If you write this code, you are almost certainly doing something terribly wrong.
kuchi
@George Why did you say that?
Johnride
@George Not necessarily, if you deal with something that has a lot of sensitive entry parameters and it is very complicated to verify the validity of each one of them, catching all kind of exceptions once the working cases are properly tested is the way to go. It will make the code clear and way less mindf*k than a huge and potentially heavy condition.
Lou Morda
Most coders I have worked with put nothing in their catch statements, so using this try catch snippet is actually better than catching a bunch of different exception types and not doing anything with it
zpon
@LouisMorda I disagree, catching every Exception subclass and not doing anything based on them (ignoring them) is worse than only catching some specific exceptions and ignoring them. If you catch some Exception types and don't do anything with the information, you have no chance of knowing what went wrong in those situations, but if you catch all Exception subclasses you have no chance of knowing what went wrong in a much large number of situations. Consider how you would handle bug reports without the information from the exceptions, like stacktraces and messages.
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You may catch multiple exceptions in single catch block.
try{ // somecode throwing multiple exceptions; } catch (Exception1 | Exception2 | Exception3 exception){ // handle exception. } 
Comments
It is bad practice to catch Exception -- it's just too broad, and you may miss something like a NullPointerException in your own code.
For most file operations, IOException is the root exception. Better to catch that, instead.
1 Comment
Pedro Sequeira
It is bad practice to catch Exception. why? downvote bad explained
Do you mean catch an Exception of any type that is thrown, as opposed to just specific Exceptions?
If so:
try { //...file IO... } catch(Exception e) { //...do stuff with e, such as check its type or log it... } 
Yes there is.
try { //Read/write file }catch(Exception ex) { //catches all exceptions extended from Exception (which is everything) } answered Jul 2, 2009 at 18:19
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