Assertions in java 1.5

[sridhanya ganapathy]

Hi All,

I was going through the book SCJP Certification [] chapter 5. In page 380 I found the below statement .
================================================================>
As with so much of Java, you can abuse the intended use of assertions, despite the best efforts of Sun's Java engineers to discourage you from doing so. For example, you're never supposed to handle an assertion failure. That means you shouldn't catch it with a catch clause and attempt to recover. Legally, however, AssertionError is a subclass of Throwable, so it can be caught. But just don't do it! If you're going to try to recover from something, it should be an exception.

To discourage you from trying to substitute an assertion for an exception, the AssertionError doesn't provide access to the object that generated it.

All you get is the String message.
================================================================>
But I have tried the below statement and it seems to compiling/running properly. Am I missing something? Appriciate your help.


================================================================>
public class S
{
public static void main(String args[])
{
try
{
int i=128;
assert (i==127);
i++;
}
catch(AssertionError e)
{
e.printStackTrace();
}
}
}

output:
> "C:\Program Files\Java\jdk1.5.0_06\bin\java.exe" -ea S
java.lang.AssertionError
at S.main(S.java:8)
================================================================>


Appriciate your help.

Thanks and Regards,
sridhanya

[Deepak Bala]

You are not supposed to catch errors. Errors are things that are so bad that, you should not catch them and try to recover. However you can catch errors and handle them, which is bad programming practise. It is legal but not a very smart thing to do.

[sridhanya ganapathy]

I do agree with it.
Error can be caught.
But in the book the phrase was like the below

-----------------------------------------------------------
To discourage you from trying to substitute an assertion for an exception, the AssertionError doesn't provide access to the object that generated it.
-----------------------------------------------------------

But i am able catch the same object and printStackTrace gives me the appropriate message.Please help me in this regard

[wise owen]

Why doesn't an AssertionError allow access to the object that generated it?