Rethrowing exceptions in Java without losing the stack trace

In C#, I can use the throw; statement to rethrow an exception while preserving the stack trace:

try
{ ...
}
catch (Exception e)
{ if (e is FooException) throw;
}

Is there something like this in Java (that doesn't lose the original stack trace)?

5

9 Answers

catch (WhateverException e) { throw e;
}

will simply rethrow the exception you've caught (obviously the surrounding method has to permit this via its signature etc.). The exception will maintain the original stack trace.

11

You can also wrap the exception in another one AND keep the original stack trace by passing in the Exception as a Throwable as the cause parameter:

try
{ ...
}
catch (Exception e)
{ throw new YourOwnException(e);
}

3

I would prefer:

try
{ ...
}
catch (FooException fe){ throw fe;
}
catch (Exception e)
{ // Note: don't catch all exceptions like this unless you know what you // are doing. ...
}

7

In Java is almost the same:

try
{ ...
}
catch (Exception e)
{ if (e instanceof FooException) throw e;
}

5

In Java, you just throw the exception you caught, so throw e rather than just throw. Java maintains the stack trace.

something like this

try
{ ...
}
catch (FooException e)
{ throw e;
}
catch (Exception e)
{ ...
}

Stack trace is prserved if you wrap the catched excetion into an other exception (to provide more info) or if you just rethrow the catched excetion.

try{ ... }catch (FooException e){ throw new BarException("Some usefull info", e); }

public int read(byte[] a) throws IOException { try { return in.read(a); } catch (final Throwable t) { /* can do something here, like in=null; */ throw t; }
}

This is a concrete example where the method throws an IOException. The final means t can only hold an exception thrown from the try block. Additional reading material can be found here and here.

1

I was just having a similar situation in which my code potentially throws a number of different exceptions that I just wanted to rethrow. The solution described above was not working for me, because Eclipse told me that throw e; leads to an unhandeled exception, so I just did this:

try
{
...
} catch (NoSuchMethodException | SecurityException | IllegalAccessException e) { throw new RuntimeException(e.getClass().getName() + ": " + e.getMessage() + "\n" + e.getStackTrace().toString());
}

Worked for me....:)

1

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