I have following two methods:

```
public static double calculateMeanInt(List<Integer> numbers) {
double sum = 0.0;
for(Integer number : numbers)
sum += number;
return sum/numbers.size();
}
public static double calculateMeanDouble(List<Double> numbers) {
double sum = 0.0;
for(Double number : numbers)
sum += number;
return sum/numbers.size();
}
```

Do you have an elegant solution (other than using type casting and Object) that will avoid the duplicate code above and will use a single method name?

Each numeric type in Java extends from `Number`

, so you can use the bounded type parameter (thanks Paul) to average all your number types in one method:

```
public static <N extends Number> double calculateMean(List<N> numbers) {
double sum = 0.0;
for (N number : numbers)
sum += number.doubleValue();
return sum / numbers.size();
}
```

e.G. like that:

```
double intMean = calculateMean(Lists.newArrayList(1,2,3,4,5));
double doubleMean = calculateMean(Lists.newArrayList(1d,2d,3d,4d,5d));
double longMean = calculateMean(Lists.newArrayList(1l,2l,3l,4l,5l));
```

Note that `Lists`

is part of Guava.