java - 从十进制度转换为六十进制度

Question

我们正在做以下练习:Sexagesimal degree 。我们想要转换十进制输入，例如

lat: 48.858222
lon: 2.2945

六十进制结果为:

48° 51′ 30″ N, 2° 17′ 40″ E

我们编写了以下代码:

import java.util.*;
public class SexagesimalDegree {

  /**
   * Convert WGS84-Coordinates from decimal degrees in sexagesimal degrees
   * 
   * @param lat Latitute as Double
   * @param lon Longtitute as Double
   * @return String "%d° %d′ %d″ %s, %d° %d′ %d″ %s" (lat_degree, lat_minute, lat_second, lat_direction,
   *                                                  lon_degree, lon_minute, lon_second, lon_direction)
   * @throws Exception 
   */
  public static String convert /*🌐🌐🌐*/ (double lat, double lon) throws Exception {
    System.out.println("lat: "+lat);
    System.out.println("lon: "+lon);
    String[] latSplitted = String.valueOf(lat).split("\\.");
    String[] lonSplitted = String.valueOf(lon).split("\\.");
    System.out.println("latSplitted: "+Arrays.toString(latSplitted));
    System.out.println("lonSplitted: "+Arrays.toString(lonSplitted));
    String latHours = latSplitted[0];
    String lonHours = lonSplitted[0];
    System.out.println("latHours: "+latHours);
    System.out.println("lonHours: "+lonHours);

    double latMinutesNumber = Double.parseDouble(latSplitted[1])*60;
    double lonMinutesNumber = Double.parseDouble(lonSplitted[1])*60;
    System.out.println("latMinutesNumber: "+latMinutesNumber);
    System.out.println("lonMinutesNumber: "+lonMinutesNumber);


    String latMinutes = String.valueOf((int)(latMinutesNumber)).substring(0,2);
    String lonMinutes = String.valueOf((int)(lonMinutesNumber)).substring(0,2);
    System.out.println("latMinutes: "+latMinutes);
    System.out.println("lonMinutes: "+lonMinutes);

    String latDecimalPart = "0"+String.valueOf(latMinutesNumber).substring(String.valueOf(latMinutesNumber).indexOf("."));
    String lonDecimalPart = "0"+String.valueOf(lonMinutesNumber).substring(String.valueOf(lonMinutesNumber).indexOf("."));
    System.out.println("latDecimalPart: "+latDecimalPart);
    System.out.println("lonDecimalPart: "+lonDecimalPart);

    System.out.println("Double.parseDouble(latDecimalPart): "+Double.parseDouble(latDecimalPart));

    double remainingLatSeconds = Integer.parseInt(latMinutes)-Double.parseDouble(latDecimalPart);
    System.out.println("remainingLatSeconds: "+remainingLatSeconds);

    return "";
  }
}

输出以下结果:

lat: 48.858222
lon: 2.2945
latSplitted: [48, 858222]
lonSplitted: [2, 2945]
latHours: 48
lonHours: 2
latMinutesNumber: 5.149332E7
lonMinutesNumber: 176700.0
latMinutes: 51
lonMinutes: 17
latDecimalPart: 0.149332E7
lonDecimalPart: 0.0
Double.parseDouble(latDecimalPart): 1493320.0
remainingLatSeconds: -1493269.0

正如您所注意到的，我们能够按预期获得小时和分钟。然而，当我们努力争取秒数时，谜题就出现了。我们需要从纬度获取小数部分:0.1493327E7，从分钟获取小数部分:0.6700。

但是，我们得到的纬度为 0.149332E7，经度为 0.0。疑问是:如何得到剩下的小数，并计算秒数？

为了能够调试它，我们已阅读:

https://www.thoughtco.com/decimal-degrees-conversion-1434592
https://stackoverflow.com/questions/36474338/converting-string-to-double-with-dotç
https://stackoverflow.com/questions/5769669/convert-string-to-double-in-java
https://stackoverflow.com/questions/27480633/converting-from-string-to-double?noredirect=1&lq=1

总而言之，我们如何在计算分钟后计算剩余的小数，从而能够得到秒？

Answer 1

首先将度数转换为整数秒，而不是处理字符串。

double latDegrees = 48.858222;
int latSeconds = (int) Math.round(latDegrees * 60 * 60); // = 175890

现在您可以使用简单的整数算术来梳理出各个部分。

int seconds = latSeconds % 60; // = 30
int minutes = (latSeconds / 60) % 60; // = 51
int degrees = (latSeconds / 60) / 60; // = 48

这是一种替代方法，如果您不熟悉模运算符 %，它可能更容易理解:

double latDegreesWithFraction = 48.858222;
int degrees = (int) latDegreesWithFraction; // = 48

double fractionalDegrees = latDegrees - degrees; // = .858222
double minutesWithFraction = 60 * fractionalDegrees; // = 51.49332
int minutes = (int) minutesWithFraction; // = 51

double fractionalMinutes = minutesWithFraction - minutes; // = .49332
double secondsWithFraction = 60 * fractionalMinutes; // = 29.6
int seconds = (int) Math.round(secondsWithFraction); // = 30