Exception Object

[Swati Singhal]

Hi,

What happens to the exception object once the exception is caught or thrown? Is it garbage collected??

[Corey McGlone]

Swats,

Please take a look at the JavaRanch naming policy. You can update your publicly displayed name to conform to our policy by clicking here.

Thank you.

With regards to your question, exception objects will be eligible for garbage collection as soon as they are no longer used, just like any other object. So, for example, if you catch an exception and handle it, the exception will be eligible for garbage collection following the catch block (assuming you didn't assign any references to it to other variables).

[Louie van Bommel]

Caught: garbage collected at end of catch block.
Thrown: garbage collected at end of block where it's finally caught.

The Exception object is created within the catch block and its lifetime ends at the end of the block. It's similar to the lifetime of a variable in an initialized for loop:

for (int i = 0; i < 10; i++) {
  // in the block
}

The lifetime of i is the block in which it is used.

An exception

try { i = Integer.parseInt(args[0]); }
 
// a unchecked subclass of RuntimeException
catch (NumberFormatException exc) 
{
  System.out.println("first argument bad:" + exc);
  exc.printStackTrace();
}

The exc object is created in the catch block and its lifetime is that block. Therefore it's free for garbage collection as the block finishes.
[ October 26, 2004: Message edited by: Louie van Bommel ]