将txt文件数据读入double

Question

我正在尝试将文本文件中的数据保存到包含双精度数的数组中。我已经让它适用于整数，但我想添加非整数数据，到目前为止我还想不通。到目前为止，这是我的代码：

public class 主类 {

public static void main(String[] args) throws FileNotFoundException {
    List<Double> E0 = Arrays.asList();
    List<Double> E1 = Arrays.asList();
    List<Double> E2 = Arrays.asList();
    List<Double> C = Arrays.asList();
    BufferedReader reader;
    try {
        reader = new BufferedReader(new FileReader("C:\Data.txt"));
        String line = reader.readLine();
        while (line != null) {
            Double lineParts = line.split(",");
            E0.add(lineParts[0]);
            E1.add(lineParts[1]); 
            E2.add(lineParts[2]);
            C.add(lineParts[3]);
            line = reader.readLine();
        }
        reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println(E0);
        System.out.println(E1);
        System.out.println(E2);
        System.out.println(C);
    }

}

这是我的数据：

1,1,4,-1
1,2,9,1
1,5,6,1
1,4,5,1
1,6,7,-1
1,1,1,-1

Answer 1

下面的代码显示了如何解析一行并将条目转换为双精度。

import java.util.Arrays;

public class ParseDouble {

    public static void main(String[] args) {
        String line = "1,2,3,-4";
        String[] lineSplit = line.split(",");
        double[] values = new double[lineSplit.length];

        for (int i = 0; i < lineSplit.length; i++) {
            values[i] = Double.parseDouble(lineSplit[i]);
        }
        System.out.println(Arrays.toString(values)); // [1.0, 2.0, 3.0, -4.0]
    }

}

使用您的代码，以下几行应该可以完成工作：

public class MainClass {

public static void main(String[] args) throws FileNotFoundException {
    List<Double> E0 = new ArrayList();
    List<Double> E1 = new ArrayList();
    List<Double> E2 = new ArrayList();
    List<Double> C = new ArrayList();
    BufferedReader reader;
    try {
        reader = new BufferedReader(new FileReader("C:\Data.txt"));
        String line = reader.readLine();
        while (line != null) {
            String[] lineParts = line.split(",");
            E0.add(Double.parseDouble(lineParts[0]));
            E1.add(Double.parseDouble(lineParts[1])); 
            E2.add(Double.parseDouble(lineParts[2]));
            C.add(Double.parseDouble(lineParts[3]));
            line = reader.readLine();
        }
        reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println(Arrays.toString(E0.toArray()));
        System.out.println(Arrays.toString(E1.toArray()));
        System.out.println(Arrays.toString(E2.toArray()));
        System.out.println(Arrays.toString(C.toArray()));
    }

}

Answer 2

你的问题的完整答案是将静态分离方法转换为完全动态解析方法，没有任何错误，这个答案是最安全的解决方案，不取决于你插入的数据有多长。

您可以借助包含双精度值列表

的列表来实现这一点

您的数据示例：

List<List<Double>> lines = new ArrayList<>();
    BufferedReader reader;
    try {
        reader = new BufferedReader(new FileReader("C:\Data.txt"));
        String line = reader.readLine();
        while (line != null) {
            List<Double> lineList = new ArrayList<>();
            String[] lineParts = line.split(",");
            for (String linePart : lineParts) {
                lineList.add(Double.valueOf(linePart));
            }
            lines.add(lineList);
            line = reader.readLine();
        }
        reader.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    System.out.println(lines);
}

此致:)

将txt文件数据读入double

Reading txt file data into doubles

java

arrays

double

filereader

bufferedreader