根据Java中的列值拆分CSV文件

Question

I want to split csv file into multiple csv files depending on column value.
Structure of csv file: Name,Id,Dept,Course

abc,1,CSE,Btech 
fgj,2,EE,Btech 

(Rows are not separated by ; at end)

If value of Dept is CSE or ME , write it to file1.csv, if value is ECE or EE write it to file2.csv and so on.

Can I use drools for this purpose? I don't know drools much.

Any help how it can be done?

This is what I have done yet:

public void run() {

    String csvFile = "C:/csvFiles/file1.csv";
    BufferedReader br = null;
    BufferedWriter writer=null,writer2=null;
    String line = "";
    String cvsSplitBy = ",";
    String FileName = "C:/csvFiles/file3.csv";
    String FileName2 = "C:/csvFiles/file4.csv";

    try {

        writer = new BufferedWriter(new FileWriter(FileName));
        writer2 = new BufferedWriter(new FileWriter(FileName2));
        br = new BufferedReader(new FileReader(csvFile));
        while ((line = br.readLine()) != null) {

               String[] values=line.split(cvsSplitBy);

            if(values[2].equals("CSE"))
            {
                writer.write(line);
            }
            else if(values[2].equals("ECE"))
            {
                writer2.write(line);
            }


        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (br != null) {
            try {
                br.close();
                writer.flush();
                writer.close();
                writer2.close();

            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

Answer 1

1) First find column index using header row or if header is not present then by index

2) Follow below algorithm which will result map of key value where key is column by which split is performed

global resultMap;

Method add(key,row) {
        data = (resultMap.containsKey(key))? resultMap.get(key):new ArrayList<String>();
        data.add(row);
        resultMap.put(key, data );
    }

Method getSplittedMap(List rows) {
        for (String currentRow : rows) {
            add(key, currentRow);
        }
        return resultMap;
    }

hope this helps.

Answer 2

FileOutputStream f_ECE = new FileOutputStream("provideloaction&filenamehere");
FileOutputStream f_CSE_ME = new FileOutputStream("provideloaction&filenamehere");
FileInputputStream fin = new FileinputStream("provideloaction&filenamehere");
int size = fin.available(); // find the length of file
byte b[] = new byte[size];
fin.read(b);
String s = new String(b); // file copied into string
String s1[] = s.split("\n");
for (int i = 0; i < s1.length; i++) {
    String s3[] = s1[i].split(",")
    if (s3[2].equals("ECE"))
        f_ECE.write(s1.getBytes());
    if (s3[2].equals("CSE") || s3.equals("EEE"))
        f_CSE_ME.write(payload.getBytes());
}