Multi tool use

Im trying to sort an arraylist that was read from a csv file to sort by last name, zip code, and state

Here is my code so far it runs but I am stuck as to where to start as far as sorting it. I have tried to make code that sorts the result variable however I have not been able to get any of it to work. Reading and printing the raw data is all I've been able to accomplish so far. Any help would be appreciated.

package csv.read.and.sort;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.io.FileWriter;
import java.util.Collections;

/**
*
* @author degen
*/
public class CSVReadAndSort {

public static void main(String args) {
BufferedReader buffread = null;

try {
String line;
buffread = new BufferedReader (new FileReader ("C:UsersdegenOneDriveDocumentsNetBeansProjectsCSV Read and SortsrccsvreadandsortITCO321_U4IP_sample_data.csv"));

// How to read file in java line by line?
while ((line = buffread.readLine()) != null) {
System.out.println("Raw CSV data: " + line);
System.out.println("Converted ArrayList data: " + ITCO321_U4IP_sample_data(line) + "n");
}

} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (buffread != null) buffread.close();
} catch (IOException ioexcept) {
ioexcept.printStackTrace();
}
}
}

// Utility which converts CSV to ArrayList using Split Operation
public static ArrayList<String> ITCO321_U4IP_sample_data(String u4ip) {
ArrayList<String> result = new ArrayList<String>();

if (u4ip != null) {
String splitData = u4ip.split("s*,s*");
for (int i = 0; i < splitData.length; i++) {
if (!(splitData[i] == null) || !(splitData[i].length() == 0)) {
result.add(splitData[i].trim());
}
}
}
return result;
}
}


readDataFromCsvFile()

1 Answer
1

Since you provide very few informations about the data, let's assume a CSV line contains the follwoing data in this order:

If I got you right ("sorts the result variable" and reffering to the return variable of ITCO321_U4IP_sample_data named result), you want to sort this result data to get it in a different order. To achieve this you don't need to sort the result list. Look at the following code:

ITCO321_U4IP_sample_data

result

public static List<String> reorder(List<String> input) {
List<String> reordered = new ArrayList<>(input.size());

reordered.add(input.get(3)); // first name
reordered.add(input.get(0)); // last name
reordered.add(input.get(1)); // zip code
reordered.add(input.get(2)); // state

return reordered;
}


This way you set (copy) every single field of a read CSV line into a new List in a new sequential order.

List

You could of course use List.sort(...) to achieve a new order. But his would result in reordering the List on every moved field. The longer the List and the more fileds to be reordered the less efficient the sorting becomes compared to the simple copying shown above.

List.sort(...)

List

PS: You got already some common hints in the comments. Some additional hints:

It's also good practice to use interface as return types. Applying this to your method you could declare it as follows:

public static List<String> ITCO321_U4IP_sample_data(String u4ip) { ... }


When using resources like a BufferedReader it's recommended to use the try-with-resource statement. But you can read the whole file in one line of code without to worry about the resource handling using the nio-API this way:

BufferedReader

Files.readAllLines(new File("ITCO321_U4IP_sample_data.csv").toPath());


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