用java读取和格式化数据

Question

我有一个作业，我必须从文本文件中读取数据。文件中的数据如下所示：

1946-01-01;07:00:00;-1.8;G 1946-01-01;13:00:00;-1.0;G 1946-01-01;18:00:00;-1.9;G 1946-01-02;07:00:00;-1.7;G 我想格式化数据并将其放入适当的数据结构中，这样我就可以搜索两个日期之间所有日期的平均温度。当我的代码是：

package algo.weatherdata;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.time.LocalDate;
import java.util.List;

/**
 * Provides methods to retrieve temperature data from a weather station file.    
 */
public class WeatherDataHandler {
    /**
     * Load weather data from file.
     * 
     * @param filePath path to file with weather data
     * @throws IOException if there is a problem while reading the file
     */
    public void loadData(String filePath) throws IOException {
        //Read all weather data
        List<String> fileData = Files.readAllLines(Paths.get(filePath));

        /**
         * TODO: Format data and put it in appropriate data structure.
         */


    }

Answer 1

您可以在行上迭代并用分隔符分隔每行（在您的示例中为;）：

public void loadData(String filePath) throws IOException {
    List<String> fileData = Files.readAllLines(Paths.get(filePath));

    String[] lineValues = str.split(";");
    // line values are stored in this array
}

然后，您可以根据自己的喜好使用数组（存储它们，处理它们）

Answer 2

让我们假设以下类将包含天气数据：

public class WeatherData {

    private LocalDateTime dateTime;
    private double temperature;
    private String tag;            // I don't really know what is 'G' mean

    public WeatherData(LocalDateTime dateTime, double temperature, String tag) {
        this.dateTime = dateTime;
        this.temperature = temperature;
        this.tag = tag;
    }
}

接下来，我们将数据文件分析为当前结构，并将它们全部收集到一个列表中：

private List<WeatherData> weatherData = new ArrayList<>();

public void loadData(String filePath) throws IOException {
    List<String> fileData = Files.readAllLines(Paths.get(filePath));
    for(String str : fileData) {
        List<String> parsed = parseData(str);
        LocalDateTime dateTime = LocalDateTime.of(dateOf(parsed.get(0)), 
                                                  timeOf(parsed.get(1)));
        double temperature = Double.parseDouble(parsed.get(2));
        String tag = parsed.get(3);

        WeatherData weather = new WeatherData(dateTime, temperature, tag);
        weatherData.add(weather);
    }

}

private List<String> parseData(String s) {
    return Arrays.asList(s.split(";"));
}

private LocalDate dateOf(String date) {
    return LocalDate.parse(date);
}

private LocalTime timeOf(String time) {
    return LocalTime.parse(time);
}

然后你可以使用一个列表在日期之间搜索并计算平均温度

Answer 3

我在我的工作空间中尝试了上面的Dinar Zaripov代码，添加了生成日期时间、温度和标签的getter方法

for循环后的继续

private static float averageTemperature(List<WeaterData> weatherData) 
{

        float sum = 0; // Variable to store the sum
        float count = 0; // Variable to keep the count

        if (weatherList != null) {
            for (WeaterData averageWeather : weatherData) {
                float value = averageWeather.getTemperature();
                System.out.println(value);
                if (value <= 0) { // Check if the number is negative
                    sum += value; // Add the value to the current sum
                    count++; // Increment the count by 1
                }
            }

        }
        return (count > 0) ? (sum /count) : 0; // Calculate the average if there were any negative numbers
    }

但我的平均值是**平均值：：1.5999999** 然而，根据数学计算，它应该是1.6。有人能告诉我怎么做吗？或者这是正确的

当我给出以下数据时，我得到了正确的平均值：）

1946-01-01;07:00:00;-1.8;A
** 1946-01-01;13:00:00;-1.1; B**
1946-01-01;18:00:00;-1.9;C
1946-01-02;07:00:00;-1.7;D