题目：写功能平均计算给定数组中数字的平均值。

测试用例：

import org.junit.Test;
import static org.junit.Assert.assertEquals;
import org.junit.runners.JUnit4;

// TODO: Replace examples and use TDD development by writing your own tests

public class SolutionTest {

    private static final double DELTA = 1e-15;

    @Test
    public void testSomething() {
        assertEquals(1, Kata.find_average(new int[]{1,1,1}), DELTA);
        assertEquals(2, Kata.find_average(new int[]{1, 2, 3}), DELTA);
        assertEquals(2.5, Kata.find_average(new int[]{1, 2, 3, 4}), DELTA);
        }
    }

我答：

public class Kata{
  public static double find_average(int[] array){
      int sum = 0;
      for(int i = 0; i < array.length; i++){
        sum += array[i];
      }
      double ave = (double)sum/array.length;
      return ave;
  }
}

网上大牛：

public class Kata{
  public static double find_average(int[] array){
      return java.util.Arrays.stream(array).average().orElse(0);
  }
}

思考

似乎java8的stream可以干很多事。