String Object. Clarification needed

Question

Say i have the following line in my program:

jobSetupErrors.append("abc");

In the case above where jobSetupErrors is a StringBuilder(), what i see happen is:

1. New String Object is created and assigned value "abc"
2. value of that String object is assigned to the existing StringBuilder object

If that is correct, and I add 1 more line ...

jobSetupErrors.append("abc");
logger.info("abc");

In the above example are we creating String object separately 2 times?

If so, would it be more proper to do something like this?

String a = "abc";
jobSetupErrors.append(a);
logger.info(a);

Is this a better approach? Please advise

Answer 1

In the above example are we creating String object separately 2 times?

No, because in Java String literals (anything in double-quotes) are interned. What this means is that both of those lines are referring to the same String, so no further optimization is necessary.

In your second example, you are only creating an extra reference to the same String, but this is what Java has already done for you by placing a reference to it in something called the string pool. This happens the first time it sees "abc"; the second time, it checks the pool and finds that "abc" already exists, so it is replaced with the same reference as the first one.

See http://en.wikipedia.org/wiki/String_interning for more information on String interning.