There are certain things
you should not do with strings, because they are immutable. For example, repeatedly adding to a string in a loop is bad:
When you do this, in each iteration of the loop, a new String object is created into which the content of the previous String object is copied, with the extra "yip" appended.
Instead of doing this, you should use StringBuilder, which is essentially a mutable String object:
So, there are certainly situations where you have to be aware what happens with your strings, and you'd better use a StringBuilder instead.