Question

How to calculating average of an array list in Java

Answer 1

import java.util.*;
 
public class MyClass {
    public static double average(List <Double> lst) {
        Double sum = 0.0;
      
        if (!lst.isEmpty()) {
            for (Double n : lst) {
                sum += n;
        }
        return sum / lst.size();
      }
      return sum;
    }
    public static void main(String args[]) {
        ArrayList<Double> arrlist = new ArrayList<Double>();
        
        arrlist.add(79.12);
        arrlist.add(28.01);
        arrlist.add(47.98);
        arrlist.add(83.87);
        arrlist.add(99.31);

        System.out.println(average(arrlist)); 
    }
}
 
 
 
 
/*
run:
 
67.658
 
*/

 

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Answer 2

import java.util.*;
 
public class MyClass {
    public static void main(String args[]) {
        ArrayList<Double> arrlist = new ArrayList<Double>();
        
        arrlist.add(79.12);
        arrlist.add(28.01);
        arrlist.add(47.98);
        arrlist.add(83.87);
        arrlist.add(99.31);
        
        OptionalDouble average = arrlist
                    .stream()
                    .mapToDouble(val -> val)
                    .average();

        System.out.println(average.getAsDouble()); 
    }
}
 
 
 
 
/*
run:
 
67.658
 
*/

 

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