Exception Handling and Garbage Collection

What is Exception ?

What is a user-defined exception?

What do you know about the garbage collector?

Why Java does not support pointers?

Does garbage collection guarantee that a program will not run out of memory?

What is finally in Exception handling?

What can prevent the execution of the code in finally block?

Explain 'try','catch' and 'finally' blocks?

Define Checked and Unchecked exception.