How to check which exception type was thrown in Java?

Question

How can I determine which type of exception was caught, if an operation catches multiple exceptions?

This example should make more sense:

try {   int x = doSomething(); } catch (NotAnInt | ParseError e) {   if (/* thrown error is NotAnInt */) {    // line 5     // printSomething   } else {     // print something else   } } 

On line 5, how can I check which exception was caught?

I tried if (e.equals(NotAnInt.class)) {..} but no luck.

NOTE: NotAnInt and ParseError are classes in my project that extend Exception.

Answer 1

If you can, always use separate catch blocks for individual exception types, there's no excuse to do otherwise:

} catch (NotAnInt e) {     // handling for NotAnInt } catch (ParseError e) {     // handling for ParseError } 

...unless you need to share some steps in common and want to avoid additional methods for reasons of conciseness:

} catch (NotAnInt | ParseError e) {     // a step or two in common to both cases     if (e instanceof NotAnInt) {         // handling for NotAnInt     } else  {         // handling for ParseError     }     // potentially another step or two in common to both cases } 

however the steps in common could also be extracted to methods to avoid that if-else block:

} catch (NotAnInt e) {     inCommon1(e);     // handling for NotAnInt     inCommon2(e); } catch (ParseError e) {     inCommon1(e);     // handling for ParseError     inCommon2(e); }  private void inCommon1(e) {     // several steps     // common to     // both cases } private void inCommon2(e) {     // several steps     // common to     // both cases } 

Answer 2

If Multiple throws are happening in a single catch() then to recognize which Exception , you could use instanceof operator.

The java instanceof operator is used to test whether the object is an instance of the specified type (class or subclass or interface).

Try this code :-

        catch (Exception e) {             if(e instanceof NotAnInt){              // Your Logic.              } else if  if(e instanceof ParseError){                               //Your Logic.             }       }