/guava/android/guava/src/com/google/common/collect/Collections2.java
requireNonNull ( nextPermutation ) ;
void calculateNextPermutation() { int j = findNextJ(); if (j == -1) { nextPermutation = null; return; } <extra_id_0> int l = findNextL(j); Collections.swap(nextPermutation, j, l); int n = nextPermutation.size(); Collections.reverse(nextPermutation.subList(j + 1, n)); } int findNextJ() {