错误：找不到合适的方法 add(ArrayList<Integer>) greatCd.add(numFactors);答案

【问题标题】：error: no suitable method found for add(ArrayList<Integer>) greatestCd.add(numFactors);错误：找不到合适的方法 add(ArrayList<Integer>) greatCd.add(numFactors);
【发布时间】：2019-01-31 16:25:55
【问题描述】：

我正在用 Java 为学校制作一个分数计算器。我正在尝试使用数组找到最大公约数，但我不断收到错误消息，告诉我没有找到适合 add(ArrayList) 的方法。基本上我要做的是将 numbFactors arraylist 和 denFactors arraylist 添加到 bestCd数组列表。

ArrayList<Integer> numFactors = new ArrayList<>();
ArrayList<Integer> denFactors = new ArrayList<>();
ArrayList<Integer> greatestCd = new ArrayList<>();

// reduce the fraction result.
// find the factors of the numerator and denominator. check
for(int i = 2; i < rn +1; ++i){
    //check if the factors go evenly. check
    if (rn%i == 0){
        numFactors.add(i);
    }

}

//Same for denominators. check
for(int i = 2; i < rd +1; ++i){
    //check if the factors go evenly. check
    if (rd%i == 0){
        denFactors.add(i);
    }

}
//Find the greatest common divisor
//Find the common factors
for(int i =0; i < numFactors.size(); i++){
    for(int j =0; j<denFactors.size(); j++){
        if(numFactors == denFactors){

           greatestCd.add(numFactors);
           greatestCd.add(denFactors);
        }
// check to see which are the same
// if they are, add them to the third arraylist
    }
}

这是我遇到的错误

 error: no suitable method found for add(ArrayList<Integer>)
                                                greatestCd.add(numFactors);
                                                          ^
    method Collection.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method List.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method AbstractCollection.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method AbstractList.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method ArrayList.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
RodriguesP1.java:159: error: no suitable method found for add(ArrayList<Integer>)

                                                greatestCd.add(denFactors);
                                                          ^
    method Collection.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method List.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method AbstractCollection.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method AbstractList.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
    method ArrayList.add(Integer) is not applicable
      (argument mismatch; ArrayList<Integer> cannot be converted to Integer)
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
2 errors

【问题讨论】：

你可能想分别使用numFactors.get(i)和denFactors.get(j)
get 和 add 有什么区别？
不，我的意思是例如greatestCd.add(numFactors.get(i)); 和 if(numFactors.get(i) == denFactors.get(j))
我没有收到你的最后一个 if 块

标签： java

【解决方案1】：

问题在于，在这一行 greatestCd.add(numFactors); 您正试图将 ArrayList 添加到另一个 ArrayList（它只需要整数，而不是另一个整数的 ArrayList）。

您可能想要做的是将numFactors 中的所有元素添加到greatestCd。使用 .addAll()。

greatestCd.addAll(numFactors);

或者对于您的示例，使用 .get(index) 从 numFactors 中添加一个。

greatestCd.add(numFactors.get(i));

【讨论】：