java - 预期为 : reference. 发现为 : double. 参数错误。怎么了？

Question

我正在编写一个代码，该代码使用递归来查找期末考试所需的最低成绩。在我的MinimumGradeFinder 类(class)中，我有以下内容:

public ArrayList<double> calculateGrades(int currIndex, double[] setNumbers,
                  double[] volatileNumbers, double targetAvg,
                  int totalCount, int maxGrade) {

  // A bunch of code

  caclulateGrades(currIndex + 1, setNumbers, volatileNumbers,
                  targetAvg, totalCount, maxGrade);
  return minCombos;
  // A private ArrayList<double> intitialized at the top of the class
}

它抛出以下错误:

MinimumGradeFinder.java:13: error: unexpected type
  public ArrayList<double> calculateGrades(int currIndex,
double[] setNumbers, double[] volatileNumbers, double
targetAvg, int totalCount, int maxGrade) {
                   ^
  required: reference
  found:    double
MinimumGradeFinder.java:58: error: cannot find symbol
      caclulateGrades(currIndex + 1, setNumbers,
volatileNumbers, targetAvg, totalCount, maxGrade);
      ^
  symbol:   method caclulateGrades(int,double[],double[],double,int,int)
  location: class MinimumGradeFinder
2 errors

exit status 1

“required:reference.found:double”是什么意思？我没有发现我调用任何参数的方式有任何问题...请帮助我。

Answer 1

替换ArrayList<double>与 ArrayList<Double> .

double是原始类型，不能用作类型参数。其对应的引用是 Double .