从HashMap中以java创建CSV文件 [英] Creating a CSV File in java from a HashMap

问题描述

我有一个hashMap在java中的一些键，每个键指示一个流。然后每个显示每个数据包的静态的值都属于该流程。

我需要做的是，基于这些值为每个流绘制图形。例如：

  Flow1：{[length，time]，[]，[]，...} 
 Flow2：{[length，time]，[length，time]，[]，...} 
  

我需要创建一个CSV文件，然后可以从MS Excel中读取。

编辑：
这里是我的hashMap：

 迭代器< Flows> iterator = myHashMap.keySet（）。iterator（）; 
 String fileName =（（args.length> 0）？args [0]：jexcel.xls）; 
 Map< String，ArrayList> csv = new HashMap< String，ArrayList>（）; 
 int i = 0; 
 
 while（iterator.hasNext（））{
 Flows键= iterator.next（）; 
 ArrayList value = myHashMap.get（key）; 
 csv.put（Flow [+ i +]，value）; 
 
 
} 
  

解决方案

如果您真的想要一个Excel文件，创建一个最好的库是 Andy Khan的JExcel 。 p>

我认为每个流程需要一个工作表，每个流有.csv对，按时间排序。

如果这些是变量对时间的图形，那么时间不是每对中的第一个值？

这是我怎么做的。它完美地适用于我提供的简单测试用例 - 它是可以扩展的工作代码。

 包jexcel; 
 
 import jxl.Workbook; 
 import jxl.write.WritableSheet; 
 import jxl.write.WritableWorkbook; 
 import jxl.write.WriteException; 
 
 import java.io.File; 
 import java.io.IOException; 
 import java.util.ArrayList; 
 import java.util.HashMap; 
 import java.util.List; 
 import java.util.Map; 
 
 public class JExcelUtils 
 {
 public static void main（String [] args）
 {
 String fileName =（（args.length> 0 ）？args [0]：jexcel.xls）; 
 Map< String，List&Pair>> csv = new HashMap< String，List&Pair>>（）
 {{
 put（Flow1，fromArrayToList（new double [] [] 
 {
 {0.0 ，0.0}，
 {0.1,1.0}，
 {0.2，2.0}，
 {0.3，3.0}，
 {0.4,4.0}，
 {0.5 ，5.0}，
}））; 
 put（Flow2，fromArrayToList（new double [] [] 
 {
 {0.0，0.0}，
 {0.1,1.0}，
 { 4.0}，
 {0.3，9.0}，
 {0.4，16.0}，
 {0.5，25.0}，
} 
}}; 
 WritableWorkbook excelContents = null; 
 
 try 
 {
文件excelFile =新文件（fileName）; 
 excelContents = createExcel（excelFile，csv）; 
 excelContents.write（）; 
} 
 catch（IOException e）
 {
 e.printStackTrace（）; 
} 
 catch（WriteException e）
 {
 e.printStackTrace（）; 
} 
 finally 
 {
 try {if（excelContents！= null）excelContents.close（）; } catch（Exception e）{e.printStackTrace（）; } 
} 
} 
 
 
 public static List< Pair> fromArrayToList（double [] [] input）
 {
 List< Pair> result = new ArrayList< Pair>（）; 
 
 for（int i = 0; i  {
 result.add（new Pair（input [i] [0] input [i] [1]））; 
} 
 
返回结果; 
} 
 
 public static WritableWorkbook createExcel（File excelFile，Map< String，List&Pair>> worksheets）throws IOException，WriteException 
 {
 WritableWorkbook result = .createWorkbook（excelFile）; 
 
 int Order = 0; 
 for（String worksheetName：worksheets.keySet（））
 {
 WritableSheet worksheet = result.createSheet（worksheetName，order ++）; 
 List< Pair> worksheetValues = worksheets.get（worksheetName）; 
 for（int row = 0; row< worksheetValues.size（）; ++ row）
 {
 worksheet.addCell（new jxl.write.Number（0，row，worksheetValues。 get（row）.getX（）））; 
 worksheet.addCell（new jxl.write.Number（1，row，worksheetValues.get（row）.getY（）））; 
} 
} 
 
返回结果; 
} 
 
} 
 
 
类对
 {
 private double x; 
 private double y; 
 
对（double x，double y）
 {
 this.x = x; 
 this.y = y; 
} 
 
 public double getX（）
 {
 return x; 
} 
 
 public double getY（）
 {
 return y; 
} 
} 
  

I have a hashMap in java in terms of some keys which each key is indicating a flow. Then each value showing statics about each packet belongs to that flow.

What I need to do is, to draw graphs for each flow based on those values. for example:

  Flow1: {[length, time],[],[],...}
  Flow2: {[length, time],[length, time],[],...}

i need to create a CSV file that then can be read from MS excel. Can anyone has the idea to give me some clues please?

Edited: here is my hashMap:

    Iterator<Flows> iterator =  myHashMap.keySet().iterator();
    String fileName = ((args.length > 0) ? args[0] : "jexcel.xls");
    Map<String, ArrayList> csv = new HashMap<String, ArrayList>();
    int i=0;

    while(iterator.hasNext()){
        Flows key = iterator.next();
        ArrayList value = myHashMap.get(key);
        csv.put("Flow["+i+"]", value);


    }

解决方案

If you really want an Excel file, the best library for creating one is Andy Khan's JExcel.

I think you'd need one worksheet per flow, with .csv pairs for each one, sorted by time.

If these are graphs of a variable versus time, wouldn't "time" be the first value in each pair?

Here's how I'd do it. It works perfectly for the simple test case I supplied - it's working code that you'll be able to extend.

package jexcel;

import jxl.Workbook;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;
import jxl.write.WriteException;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class JExcelUtils
{
    public static void main(String[] args)
    {
        String fileName = ((args.length > 0) ? args[0] : "jexcel.xls");
        Map<String, List<Pair>> csv = new HashMap<String, List<Pair>>()
        {{
            put("Flow1", fromArrayToList(new double[][]
            {
                { 0.0, 0.0 },
                { 0.1, 1.0 },
                { 0.2, 2.0 },
                { 0.3, 3.0 },
                { 0.4, 4.0 },
                { 0.5, 5.0 },    
            }));
            put("Flow2", fromArrayToList(new double[][]
            {
                { 0.0, 0.0 },
                { 0.1, 1.0 },
                { 0.2, 4.0 },
                { 0.3, 9.0 },
                { 0.4, 16.0 },
                { 0.5, 25.0 },
            }));
        }};
        WritableWorkbook excelContents = null;

        try
        {
            File excelFile = new File(fileName);
            excelContents = createExcel(excelFile, csv);
            excelContents.write();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        catch (WriteException e)
        {
            e.printStackTrace();
        }
        finally
        {
            try { if (excelContents != null) excelContents.close(); } catch (Exception e) { e.printStackTrace(); }
        }
    }


    public static List<Pair> fromArrayToList(double [][] input)
    {
        List<Pair> result = new ArrayList<Pair>();

        for (int i = 0; i < input.length; ++i)
        {
            result.add(new Pair(input[i][0], input[i][1]));            
        }

        return result;
    }

    public static WritableWorkbook createExcel(File excelFile, Map<String, List<Pair>> worksheets) throws IOException, WriteException
    {
        WritableWorkbook result = Workbook.createWorkbook(excelFile);

        int order = 0;
        for (String worksheetName : worksheets.keySet())
        {
            WritableSheet worksheet = result.createSheet(worksheetName, order++);
            List<Pair> worksheetValues = worksheets.get(worksheetName);
            for (int row = 0; row < worksheetValues.size(); ++row)
            {
                worksheet.addCell(new jxl.write.Number(0, row, worksheetValues.get(row).getX()));
                worksheet.addCell(new jxl.write.Number(1, row, worksheetValues.get(row).getY()));
            }
        }

        return result;
    }

}


class Pair
{
    private double x;
    private double y;

    Pair(double x, double y)
    {
        this.x = x;
        this.y = y;
    }

    public double getX()
    {
        return x;
    }

    public double getY()
    {
        return y;
    }
}

这篇关于从HashMap中以java创建CSV文件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！