为什么Math.pow(x,y)算作双重？

Question

我正在编写一个Java程序来计算在My Singing Monsters中将怪物提升到一定水平需要多少食物.当我运行程序时,它说,"无法从double转换为int".有人可以解释为什么会这样吗？这是程序.

int totalFood = 0;
int level = 1;
int levelMeal = 5*(Math.pow(2,level-1));
int mealNumber = 1;
int levelGoal = 1;
while(level != levelGoal)
{
  if(mealNumber != 5)
  {
    mealNumber += 1;
    totalFood += levelMeal;
  }
  else if(mealNumber == 5)
  {
    mealNumber = 0;
    level += 1;
  }
}
if(level == levelGoal)
{
  println("The total amount of food required for a monster to reach level " + levelGoal + " is " + totalFood + " food.");
}

Answer 1

你必须这样做:

int levelMeal = (int) (5*(Math.pow(2,level-1)));
                  ^
           this is a cast

正如您在文档中看到的那样,按设计Math.pow()返回double,但如果您需要,int则必须执行显式强制转换.