You won't need to know Stringss to the level of the example you have given. The actual objective that mentions Strings says the following.
"Develop code that uses the primitive wrapper classes (such as Boolean, Character, Double, Integer, etc.), and/or autoboxing & unboxing. Discuss the differences between the
String, StringBuilder, and StringBuffer classes."
So make sure you know about the StringBuilder and Buffer classes (not a huge topic).