Java Utililty Methods List Average

double avg = 0;
for (T i : numbers)
    avg += i.doubleValue();
return avg / numbers.size();

int r = 0;
int g = 0;
int b = 0;
int a = 0;
int col;
int count = colours.size();
for (int i = 0; i < count; i++) {
    col = colours.get(i);
...

long sum = 0;
for (Long l : durations) {
    sum = sum + l;
long avg = 0;
if (durations.size() > 0) {
    avg = (long) (sum / durations.size());
return avg;

long result = 0;
int start = tapTimestamps.size() - (n + 1);
if (start < 0) {
    start = 0;
    n = tapTimestamps.size() - 1;
if (n == 0) {
    return 0;
...

if (longList == null || longList.isEmpty()) {
    return devByZero;
double sd = 0.0d;
for (long l : longList) {
    sd += Math.pow(l - average, 2);
sd = Math.sqrt(sd / (double) longList.size());
...