Java 8 stream average for float

Question

I have the following model:

public class WeightChange {      private float value;      public float getValue() {         return value;     }      public void setValue(float value) {         this.value = value;     }  } 

and collection:

private List<WeightChange> weightChanges; 

I have implemented function that gets average weight value using Java 8 features:

public float getAvgChangedWeight() {     return (float) weightChanges.stream().mapToDouble(WeightChange::getValue).average().getAsDouble();       } 

Could you please help improve it because I don't think that casting to double is a good idea.

Also it throws an exception when the weightChanges collection is empty. How does one improve it in this case?

Answer 1

To answer the second part of your question, if you want to avoid the exception when the list is empty and return some double value, use orElse instead of getAsDouble:

return weightChanges.stream()     .mapToDouble(WeightChange::getValue)     .average()     .orElse(Double.NaN);