获取当前月的前十二个月

Calendar now = Calendar.getInstance();
for (int i = 0; i < 12; i++) {
    int k = now.get(Calendar.YEAR);
    int j = now.get(Calendar.MONTH) + 1 - i;
    String yearMonth = "";
    if (j >= 1) {
        yearMonth = k + "-" + (j >= 10 ? "" : "0") + j;
    } else {
        int p = 11 - i;
        int m = now.get(Calendar.YEAR) - 1;
        int n = now.get(Calendar.MONTH) + 2 + p;
        yearMonth = m + "-" + (n >= 10 ? "" : "0") + n;
    }
　　　System.out.println(yearMonth);
}