Java — junior level
2 questions pitched at this level, most-asked first.
Is Java pass-by-value or pass-by-reference?
Java is always pass-by-value, with no exceptions. For an object the value copied is the reference, which is why a method can mutate your object but can never swap or replace it.
Asked constantlyjunior0–6 yrs8 min readOopWhat is the difference between String, StringBuilder and StringBuffer?
String is immutable, so every change allocates a new one. StringBuilder is a growable buffer you mutate in place. StringBuffer is the same thing with every method synchronized, which you almost never need. Concatenating in a loop is the only case where the difference is dramatic — and it is dramatic.
Asked constantlyjunior0–6 yrs9 min readStrings