Question

我有一个关于如何使用数组执行计算的问题。在我的例子中，我需要执行数组的计算，然后在main方法中调用它。我在返回类型中进行了计算，并且编译器抱怨double不能转换为double []所以我尝试获取数组的长度，但仍然得到相同的警告。我怎样才能解决这个问题？任何帮助将不胜感激。以下是我的代码：

// calcGravity returns an array of doubles containing teh gravity values
//and takes two arrays of doubles as parameters for the radius values and mass
public static double[] calcGravity(double[] radius, double[] mass)
{
    // fill in code here
        return (6.67E-17) * mass.length / Math.pow(radius.length, 2);
    // The formula to calculate gravity is:
    // 6.67E-17 times the massOfPlanet divided by the radius of the planet squared
}

Answer 1

public static double[] calcGravity(double[] radius, double[] mass)
{
    double[] ret = new double[radius.length];
    for (int i=0;i<radius.length;i++) {
      // fill in code here
      ret[i] = (6.67E-17) * mass[i] / Math.pow(radius[i], 2);
      // The formula to calculate gravity is:
      // 6.67E-17 times the massOfPlanet divided by the radius of the planet squared
   }
   return ret;
}

Answer 2

您需要分别对每一行进行计算。

double[] gravities = new double[radius.length]();

for (int i =0; i<radius.length;i++) {
  gravities[i] = (6.67E-17) * mass[i] / Math.pow(radius[i], 2);
}
return gravities;

Answer 3

double[]是一系列双打。你只是计算一个数字。当您尝试返回double并且返回类型为double[]时，编译器无法转换它。

你的计算错了。 radius和mass的长度不是半径和质量。它们每个都包含一串数字，每个数字都是半径和质量。您想要计算每个质量/半径对的每个重力并返回包含以下内容的新数组：

public static double[] calcGravity(double[] radius, double[] mass)
{
    // Check that you have the same number of radii as masses
    if (radius.length != mass.length)
      throw new IllegalArgumentException("Cannot calculate gravities with unequal radii and masses.");

    double[] gravity = new double[radius.length];
    for (int i = 0; i < radius.length; i++) {
      double[i] = (6.67E-17) * mass[i] / Math.pow(radius[i], 2);
    }
    return gravity;
}

Answer 4

如果您正在访问mass.length和radius.length，您将获得这些数组中的元素数量。

所以你必须编写一个循环来迭代这些数组中的所有值。

public static double[] calcGravity(double[] radius, double[] mass) {
    int size = radius.length;

    if (size != mass.length) {
        throw IllegalArgumentException("can't calculate with different count of array elements!");
    }

    double[] sums = new double[size];

    for (int i = 0; i < size; i++) {
       sums[i] = (6.67E-17) * mass[i] / Math.pow(radius[i], 2);
    }

    return sums;
}

Answer 5

public static double[] calcGravity(double[] radius, double[] mass){
   double[] grav = new double[radius.length]();
   for (int i =0; i<radius.length;i++) {
      grav[i] = (6.67E-17) * mass[i] / Math.pow(radius[i], 2);
   }
   return grav;
}

使用数组执行计算

5 个答案: