Question

我正在尝试按如下方式创建一个程序：

给出来自csv / text文件的数据，例如：

Colour, date, time, noise
red, 03/11/2014, 13:00, 10
blue, 04/11/2014, 14:00, 15
pink, 03/11/2014, 15:00, 50
blue, 05/11/2014, 14:00, 15

如何从15:00 - 17:00返回范围，打印出范围内的行，并确保还返回17:00的行

因此，如果用户输入03/11/2014和04/11/2014 ..它将输出：

red, 03/11/2014, 13:00, 10
blue, 04/11/2014, 14:00, 15
pink, 03/11/2014, 15:00, 50

这是我的尝试：

package readFile;

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

public class read {
public static void main(String[] args) {
    // TODO code application logic here
    File fileName = new File("Data.csv");
    try {
        String startToken = "03/11/2014";
        String endToken = "04/11/2014";
        boolean output = false;

        Scanner scan = new Scanner(fileName);
        while (scan.hasNextLine()) {
            String line = scan.nextLine();
            if (!output && line.indexOf(startToken) >= -1) {
                output = true;
                line = line.substring(line.indexOf(startToken)+startToken.length());
            } else if (output && line.indexOf(endToken) > -1) {
                output = false;
                System.out.println(line.substring(0, line.indexOf(endToken)));
            }

            if (output) {
                System.out.println(line);
            }
        }
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
}

}

但输出是：

ate, time, noise
red, 03/11/2014, 13:00, 10
blue, 
, 15:00, 50
blue, 05/11/2014, 14:00, 15

任何帮助将不胜感激

Answer 1

您可以使用http://csvjdbc.sourceforge.net/并使用选择查询。或直接将行导入某个数据库（在内存或真正的大数据库中） - 对于cvs处理，有许多库，如opencsv和通过sql查询选择值。

Answer 2

以下是如何实现它的示例。 Java实现尝试从给定的字符串创建Date对象并进行比较。

输入（Data.csv）：

red, 03/11/2014, 13:00, 10
blue, 04/11/2014, 14:00, 15
pink, 03/11/2014, 15:00, 50
blue, 05/11/2014, 14:00, 15

输出：

Entry [colour=red, date=03/11/2014, time=13:00, noise=10]
Entry [colour=blue, date=04/11/2014, time=14:00, noise=15]
Entry [colour=pink, date=03/11/2014, time=15:00, noise=50]

实现：

import java.io.File;
import java.io.FileNotFoundException;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;

public class RangeCalculator {
    private File file;
    public static final String DATE_FORMAT = "dd/MM/yyyy";

    public class Entry {
        String colour;
        String date;
        String time;
        String noise;

        public Entry(String colour, String date, String time, String noise) {
            super();
            this.colour = colour;
            this.date = date;
            this.time = time;
            this.noise = noise;
        }

        // implement getters and setters here if necessary

        @Override
        public String toString() {
            return "Entry [colour=" + colour + ", date=" + date + ", time="
                    + time + ", noise=" + noise + "]";
        }
    }

    public RangeCalculator(String fileName) {
        file = new File(fileName);
    }

    private List<Entry> computeRange(String from, String to)
            throws FileNotFoundException, ParseException {

        List<Entry> result = new LinkedList<>();

        SimpleDateFormat formatter = new SimpleDateFormat(DATE_FORMAT);
        Date fromDate = formatter.parse(from);
        Date toDate = formatter.parse(to);

        Scanner scanner = new Scanner(file);
        scanner.useDelimiter("[,\n]");

        // maybe you want/need to skip the first line of the file
        // if (scanner.hasNextLine()) {
        //     scanner.nextLine();
        // }

        while (scanner.hasNextLine()) {         
            String color = scanner.next();
            String date = scanner.next().substring(1);
            String time = scanner.next().substring(1);
            String noise = scanner.next().substring(1);

            Date currDate = formatter.parse(date);
            if (!currDate.before(fromDate) && !currDate.after(toDate)) {
                result.add(new Entry(color, date, time, noise));
            }
        }

        scanner.close();
        return result;
    }

    private void printEntries(List<Entry> entries) {
        for (Entry entry : entries) {
            System.out.println(entry.toString());
        }
    }

    public static void main(String[] args) {
        RangeCalculator app = new RangeCalculator("Data.csv");

        List<Entry> calculatedEntries = null;
        try {
            calculatedEntries = app.computeRange("03/11/2014", "04/11/2014");
        } catch (FileNotFoundException e) {
            System.err.println("ERROR: File not found!");
            System.exit(1);
        } catch (ParseException e) {
            System.err.println("ERROR: Wrong date format!");
            System.exit(1);
        }

        app.printEntries(calculatedEntries);
        System.exit(0);
    }
}

在Java中查找范围

2 个答案: