java将一个方法数组的一部分实现为一个新方法

Question

我有一个项目，我必须根据给定的月份、年份或日期查找数据。如果为空，则返回该年/日/月的所有数据。我得到了第一种读取文件并将数据放入数组的方法；每一行都是特定时间的数据，格式为

#站点_代码年月日时分秒值_unc值经纬度海拔高度入口_高度仪表qcflag

数据字符串示例如下：

BRW 1973 1 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

BRW 1973 1 2 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

问题是，我不知道如何获取第一个方法数组的部分，以便收集所调用的年/日/月的所有数据

这是我的代码：

public ArrayList<CO2Data> loadData(String filename) throws FileNotFoundException {

    ArrayList array = new ArrayList();
    String input = "";
    try {
        Scanner scan = new Scanner(new File("input.txt"));
         while ((input = scan.next()) != null){
        input = scan.next();
        if (input == "BRW"){
            array.add(scan.nextLine());
        }
        }
        scan.close();
    }
    catch (FileNotFoundException exception)
    {
        System.out.println("could not find file");
    }

    return array;
}

@Override
public ArrayList<CO2Data> getData(Integer year, Integer month, Integer day) {

    ArrayList array = null;
    for(int i = 0;  != null; i++){
        if (year == nextLoadData || year == null){
        if (month == nextLoadData || month == null){
        if (day == nextLoadData || day == null){
        array.add();
        }}
    }
    return array;
}

Answer 1

我将添加完整的解决方案，以便您可以研究和更改它

首先，我们有CO2Data类来保存一行数据。也许你可以查一下Lesson: Object-Oriented Programming Concepts

二氧化碳数据：

public class CO2Data
{
    private String site_code;
    private String year;
    private String month;
    private String day;
    private String hour;
    private String minute;
    private String second;
    private String value;
    private String value_unc;
    private String nvalue;
    private String latitude;
    private String longitude;
    private String altitude;
    private String elevation;
    private String intake_height;
    private String instrument;
    private String qcflag;

    public CO2Data(){

    }

    public String getSite_code ( )
    {
        return site_code;
    }
    public void setSite_code ( String site_code )
    {
        this.site_code = site_code;
    }
    public String getYear ( )
    {
        return year;
    }
    public void setYear ( String year )
    {
        this.year = year;
    }
    public String getMonth ( )
    {
        return month;
    }
    public void setMonth ( String month )
    {
        this.month = month;
    }
    public String getDay ( )
    {
        return day;
    }
    public void setDay ( String day )
    {
        this.day = day;
    }
    public String getHour ( )
    {
        return hour;
    }
    public void setHour ( String hour )
    {
        this.hour = hour;
    }
    public String getMinute ( )
    {
        return minute;
    }
    public void setMinute ( String minute )
    {
        this.minute = minute;
    }
    public String getSecond ( )
    {
        return second;
    }
    public void setSecond ( String second )
    {
        this.second = second;
    }
    public String getValue ( )
    {
        return value;
    }
    public void setValue ( String value )
    {
        this.value = value;
    }
    public String getValue_unc ( )
    {
        return value_unc;
    }
    public void setValue_unc ( String value_unc )
    {
        this.value_unc = value_unc;
    }
    public String getNvalue ( )
    {
        return nvalue;
    }
    public void setNvalue ( String nvalue )
    {
        this.nvalue = nvalue;
    }
    public String getLatitude ( )
    {
        return latitude;
    }
    public void setLatitude ( String latitude )
    {
        this.latitude = latitude;
    }
    public String getLongitude ( )
    {
        return longitude;
    }
    public void setLongitude ( String longitude )
    {
        this.longitude = longitude;
    }
    public String getAltitude ( )
    {
        return altitude;
    }
    public void setAltitude ( String altitude )
    {
        this.altitude = altitude;
    }
    public String getElevation ( )
    {
        return elevation;
    }
    public void setElevation ( String elevation )
    {
        this.elevation = elevation;
    }
    public String getIntake_height ( )
    {
        return intake_height;
    }
    public void setIntake_height ( String intake_height )
    {
        this.intake_height = intake_height;
    }
    public String getInstrument ( )
    {
        return instrument;
    }
    public void setInstrument ( String instrument )
    {
        this.instrument = instrument;
    }
    public String getQcflag ( )
    {
        return qcflag;
    }
    public void setQcflag ( String qcflag )
    {
        this.qcflag = qcflag;
    }

    @Override
    public String toString ( )
    {
        return "CO2Data [site_code="    + site_code + ", year=" + year + ", month=" + month + ", day="
                + day + ", hour=" + hour + ", minute=" + minute + ", second=" + second + ", value="
                + value + ", value_unc=" + value_unc + ", nvalue=" + nvalue + ", latitude="
                + latitude + ", longitude=" + longitude + ", altitude=" + altitude + ", elevation="
                + elevation + ", intake_height=" + intake_height + ", instrument=" + instrument
                + ", qcflag=" + qcflag + "]";
    }



}

实现了方法的MainClass：

1) read data from the file and save it on a CO2Data List.

2) get data from the previous list matching the results.

3) print :D

Note: Do not forget to change PathToFile with yours.

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Test
{

    public static void main ( String [ ] args )
    {

        List<CO2Data> readList = loadData ( "PathToFile" );
        if ( readList != null )
        {
            List<CO2Data> dataFound = getData ( readList , "1973" , "1" , "1" );

            if( dataFound != null )
            {
                //separator
                System.out.println ( "                    " );

                //print results
                for(int i = 0; i < dataFound.size ( ); i++)
                {
                    System.out.println ( dataFound.get ( i ).toString ( ) );
                }
            }
        }
    }

    //Read data from the file
    public static List<CO2Data> loadData(String filename)
    {

        List<CO2Data> listCO2Data = new ArrayList < CO2Data >( );
        try {
            Scanner scan = new Scanner(new File(filename));
            while (scan.hasNextLine ( ))
            {
                CO2Data data = new CO2Data ( );
                data.setSite_code(scan.next());
                data.setYear(scan.next());
                data.setMonth(scan.next());
                data.setDay(scan.next());
                data.setHour(scan.next());
                data.setMinute(scan.next());
                data.setSecond(scan.next());
                data.setValue(scan.next());
                data.setValue_unc(scan.next());
                data.setNvalue(scan.next());
                data.setLatitude(scan.next());
                data.setLongitude(scan.next());
                data.setAltitude(scan.next());
                data.setElevation(scan.next());
                data.setIntake_height(scan.next());
                data.setInstrument(scan.next());
                data.setQcflag(scan.next());
                //print adds just for informational purposes
                System.out.println ( data.toString ( ) );
                listCO2Data.add ( data );
            }
            scan.close();
        }
        catch (FileNotFoundException exception)
        {
            exception.printStackTrace ( );
            System.out.println("Could not find file");
        }

        return listCO2Data.isEmpty ( ) ? null : listCO2Data;
    }

    //get data with matching dates
    public static List < CO2Data > getData(List<CO2Data> data, String year, String month, String day) 
    {
        List < CO2Data > dataFound = new ArrayList<> ( );

        for(CO2Data current : data)
        {
            if( current.getYear ( ).equals ( year ) &&
                    current.getMonth ( ).equals ( month ) &&
                    current.getDay ( ).equals ( day ))
            {
                dataFound.add ( current );
            }
        }
        return dataFound.isEmpty ( ) ? null : dataFound ;
    }
}

输入。txt:

BRW 1973 1 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

BRW 1973 2 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

BRW 1973 3 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

BRW 1973 4 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

BRW 1973 5 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

BRW 1973 1 1 0 0 0 -999.99 -99.99 0 71.323 -156.611 27.0 11.0 16.0 NA *..

输出：

CO2Data [site_code=BRW, year=1973, month=1, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
CO2Data [site_code=BRW, year=1973, month=2, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
CO2Data [site_code=BRW, year=1973, month=3, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
CO2Data [site_code=BRW, year=1973, month=4, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
CO2Data [site_code=BRW, year=1973, month=5, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
CO2Data [site_code=BRW, year=1973, month=1, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
                    
CO2Data [site_code=BRW, year=1973, month=1, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]
CO2Data [site_code=BRW, year=1973, month=1, day=1, hour=0, minute=0, second=0, value=-999.99, value_unc=-99.99, nvalue=0, latitude=71.323, longitude=-156.611, altitude=27.0, elevation=11.0, intake_height=16.0, instrument=NA, qcflag=*..]

我还在代码中添加了一些注释。 如果你对代码有任何疑问，请不要犹豫，我会相应地编辑我的答案。 祝你好运

Answer 2

我想你需要在这里做一些重新设计，让事情变得更简单。我会提出一些建议，如果你在理解上有困难，你可以在评论中告诉我

您已经有了一个CO2Data类，它大概存储了文件中一行的信息。理想情况下，它应该有一个方法，可以接受一个输入字符串并转换为这些对象之一。让我们假设它看起来像：

class CO2Data {
    private static final Pattern PATTERN = Pattern.compile("(\\s{3}) (\\d{4})");

    private final String siteCode;
    private final LocalDataTime timeOfReading;

    private CO2Data(String siteCode, int year) {
        this.siteCode = siteCode;
        this.timeOfReading = LocalDataTime.of(year, 1, 1, 1, 1);

    public static CO2Data createFromLine(String line) {
        Matcher matcher = PATTERN.match(line);
        if (matcher.matches()) {
            String siteCode = matcher.group(1);
            int year = Integer.parseInt(matcher.group(2));
            return new CO2Data(siteCode, year);
        } else {
            throw new IllegalArgumentException("Incorrectly formatted line");
        }
    }
}

为了清晰起见，我将其简化为站点代码和年份，但您可以非常简单地扩展到其他领域

从文件读取的方法应返回以下对象的列表：

public List<CO2Data> getDataFromFile(Path filepath) throws IOException {
    return Files.lines(filepath)
        .map(CO2Data::createFromLine)
        .collect(Collectors.toList());
}

然后，按年份和月份筛选的方法可以获取以下对象的列表：

public List<CO2Data> search(List<CO2Data> list, Integer year) {
    return list.stream()
        .filter(d -> year == null || d.getTime().getYear() == year)
        .collect(Collectors.toList());
}

请注意，我在这里使用了Java8特性