如何从 ArrayList<String> 转换为 double[]？

Question

我有一个这样的 ArrayList：

[5, 181, 138, 95, 136, 179]

我想做的是将此列表转换为双 []。像这样的东西。

double[] Fails = new double[]{5, 181, 138, 95, 136, 179};

这是我的代码：

    ArrayList<String> DatesList = new ArrayList<String>();
    ArrayList<String> FailList = new ArrayList<String>();


    while (rs2.next()) {
        DatesList.add(rs2.getString("Date"));
        FailList.add(rs2.getString("fail"));
    }

    double[] Fails = new double[]{FailList}; //obviously it doesn't work..

有什么方法可以将 ArrayList 转换为 double[]？

Answer 1

List<String> failList = new ArrayList<>();

while (rs2.next()) {        //whatever that is (copied from OP)
    failList.add(rs2.getString("fail"));
}

double[] failsArray = new double[failList.size()]; //create an array with the size of the failList

for (int i = 0; i < failList.size(); ++i) { //iterate over the elements of the list
    failsArray[i] = Double.parseDouble(failList.get(i)); //store each element as a double in the array
}

这段代码的作用是，它首先创建一个failsArray大小为failList. 然后，它遍历failList并将每个项目解析为 double 并将其存储在failsArray.