java - 将字符串解析为 GregoriamCalendar 类型以在 ArrayList 中使用时遇到问题

Question

所以我在这里遇到了一些麻烦 - 我正在尝试创建一个类来从雅虎下载历史股票市场数据。基本上，在第 64 行，我需要将 yyyy-MM-dd 形式的字符串解析为 GregorianCalendar 类型。我已经尝试了一段时间，并在此处和其他地方查看其他解决方案 - 虽然我可以将字符串解析为公历，但我无法将其以相同的形式 yyyy-MM-dd 添加到 ArrayList 日期。我使用 .split(,) 将 csv 的每一行拆分为单独的元素，所有其他类型都是 double 和整数，这很容易。

line 返回一个字符串，例如: 2015-11-12,116.260002,116.82,115.650002,115.720001,32262600,115.720001

提前致谢!

    public StockDownloader(String symbol, GregorianCalendar start, GregorianCalendar end) { 
        dates = new ArrayList<GregorianCalendar>(); 
        opens = new ArrayList<Double>(); 
        highs = new ArrayList<Double>(); 
        lows = new ArrayList<Double>();
        closes = new ArrayList<Double>();
        volumes = new ArrayList<Integer>();
        adjCloses = new ArrayList<Double>(); 

        //deconstructed URL
        String url = "http://real-chart.finance.yahoo.com/table.csv?s="+symbol+
                "&a="+start.get(Calendar.MONTH)+
                "&b="+start.get(Calendar.DAY_OF_MONTH)+
                "&c="+start.get(Calendar.YEAR)+
                "&d="+end.get(Calendar.MONTH)+
                "&e="+end.get(Calendar.DAY_OF_MONTH)+
                "&f="+end.get(Calendar.YEAR)+
                "&g=d&ignore=.csv";

        try { 
            URL yhoofin = new URL(url); //creates URL from String url
            URLConnection data = yhoofin.openConnection(); //invokes openConnection method on URL
            Scanner input = new Scanner(data.getInputStream()); //Returns an input stream that reads from this open connection.
            if(input.hasNext()) //skip line, it's just the header
                input.nextLine(); //advances to next line

            //start reading data
            while(input.hasNextLine()) {
                String line = input.nextLine();

                String[] splitLine = line.split(","); 

>>Problem here  //dates.add( add the date );
                opens.add(Double.parseDouble(splitLine[OPEN]));
                highs.add(Double.parseDouble(splitLine[HIGH]));
                lows.add(Double.parseDouble(splitLine[LOW]));
                closes.add(Double.parseDouble(splitLine[CLOSE]));
                volumes.add(Integer.parseInt(splitLine[VOLUME]));
                adjCloses.add(Double.parseDouble(splitLine[ADJCLOSE]));


            }
        }
        catch(Exception e) { //catch any error (exception) that happens
            System.err.println(e);
        }
    }

Answer 1

您应该将日期存储在列表中，而不是 GregorianCalendar 而是日期:

List<Date> dates = new ArrayList<>()

然后您可以使用 SimpleDateFormat 解析日期:

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
...
dates.add(format.parse(splitLine[0]));

SimpleDateFormat 可以帮助您将日期格式化为字符串，例如:

SimpleDateFormat newFormat = new SimpleDateFormat("dd-MM-yyyy HH"); //another format
String formattedDate = newFormat.format(date); //14-11-2015 11

http://docs.oracle.com/javase/7/docs/api/java/text/SimpleDateFormat.html http://docs.oracle.com/javase/7/docs/api/java/util/Date.html