String count in the pool with println

Question

I am preparing for the OCA SE 7 exam, and some of these questions are really (!) tricky.

In one of the books Im using I found an error I think, so I would like to co

Answer 1

It should be 2 strings: "autumn" and "false". The first is created by the first line. The second is created by the second line because the compiler would optimize it to just:

System.out.println(false);

which ends up calling PrintStream#print(boolean):

public void print(boolean b) {
    write(b ? "true" : "false");
}

This is what happens at runtime, i.e. after the code is executed. However, at the level of the constant pool stored in the bytecode, only 1 string constant is created which is "autumn" in the classfile of the class which contains your main method. You can verify this by running:

javap -c -verbose ClassName

Answer 2

true and false are not String objects, so they do not count. Even though the exam questions are supposed to be tricky, it's goal is to check the understanding of general concepts. Which is in this case: during class loading (before running), the string literals are loaded to the constant pool. So "autumn" and "summer" will be in the constant pool.

It is described here nicely: http://www.javaranch.com/journal/200409/ScjpTipLine-StringsLiterally.html