java ？: 问题

Question

return (compare(firstname1, firstname2) == 0 ?
(compare(lastname1, lastname2) == 0 ? (compare(sex1, sex2) == 0 ? (compare(age1, age2) == 0 ? 0 :
compare(age1, age2)) :
compare(sex1, sex2)) :
compare(lastname1, lastname2)) :
compare(firstname1, firstname2));
"："后的是什么意思