new String overriding the previous String

Ok, I want to ask whether this code fragment memory efficient or not:

String str =new String("The first value");

...//some code here

str =new String("The second value");

I mean what happens to the memory? Is it properly released from the first object?

And if I do this hundred of times wil it be ok?

[485 byte] By [prnga] at [2007-11-27 6:41:01]