What does this code mean?

Question

int mCurrentIndex = 0;
mCurrentIndex = (mCurrentIndex+1) % mQuiz.length;

Ps- mQuiz is in an instance of array object

Answer 1

I suppose that :

mQuiz.length is the number of questions in a Quiz
Let it be 5 for example

0%5 = 0 hence index 0, so it returns the question on index 0.
1%5 = 1 hence index 1, so it returns the question on index 1.
2%5 = 2
3%5 = 3
4%5 = 4
5%5 = 0
...

As a result, you loop in quiz questions.

Your code's equivalent is :

if (mCurrentIndex + 1 < mQuiz.length) {
mCurrentIndex++;
} else {
mCurrentIndex = 0;
}