What is the point of the finally block?

Question

Syntax aside, what is the difference between

try {
}
catch() {
}
finally {
    x = 3;
}

and

try {
}
catch() {
}

x = 3;
         


        

Answer 1

The finally block is in the same scope as the try/catch, so you will have access to all the variables defined inside.

Imagine you have a file handler, this is the difference in how it would be written.

try
{
   StreamReader stream = new StreamReader("foo.bar");
   stream.write("foo");
}
catch(Exception e) { } // ignore for now
finally
{
   stream.close();
}

compared to

StreamReader stream = null;
try
{
    stream = new StreamReader("foo.bar");
    stream.write("foo");
} catch(Exception e) {} // ignore

if (stream != null)
    stream.close();

Remember though that anything inside finally isn't guaranteed to run. Imagine that you get an abort signal, windows crashes or the power is gone. Relying on finally for business critical code is bad.