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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.  
  11.  
  12. 	interface AverageMaker<T extends Number> {
  13.     T initialResult();
  14.     T add(T a, Number b);
  15.     T divideByCount(T a, int b);
  16. }
  17.  
  18. public static <T extends Number, R extends Number> R averageValue(Iterable<T> items, AverageMaker<R> maker) {
  19.     R res = maker.initialResult();
  20.     int count = 0;
  21.     for (T val : items) {
  22.         res = maker.add(res, val);
  23.         count++;
  24.     }
  25.     return maker.divideByCount(res, count);
  26. }
  27.  
  28. 	static final AverageMaker<Double> doubleAvg = new AverageMaker<Double>() {
  29.     	public Double initialResult() { return 0.0; }
  30.         public Double add(Double a, Number b) { return a + b.doubleValue(); }
  31.         public Double divideByCount(Double a, int b) { return a/b; }
  32.     };
  33. 	static final AverageMaker<Integer> intAvg = new AverageMaker<Integer>() {
  34.     	public Integer initialResult() { return 0; }
  35.         public Integer add(Integer a, Number b) { return a + b.intValue(); }
  36.         public Integer divideByCount(Integer a, int b) { return a/b; }
  37.     };
  38.  
  39. 	public static void main (String[] args) throws java.lang.Exception
  40. 	{
  41. 		List<Integer> a = new ArrayList<Integer>();
  42. 		a.add(4);
  43. 		a.add(8);
  44. 		a.add(91);
  45.         a.add(18);
  46.         double avgDouble = averageValue(a, doubleAvg);
  47.         int avgInt = averageValue(a, intAvg);
  48.         System.out.println(avgDouble);
  49.         System.out.println(avgInt);
  50. 	}
  51. }
Success #stdin #stdout 0.1s 320256KB
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https://ideone.com/hx0jF1
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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