java class to read csv files

Question

Here is my class to read a csv file and I was wondering if there is any improvements that I should do. I feel there are some performance improvements or in exception handling because I just took IO exceptions.

package com.mypackage.utils;
import com.opencsv.CSVParserBuilder;
import com.opencsv.CSVReader;
import com.opencsv.CSVReaderBuilder;
import com.opencsv.enums.CSVReaderNullFieldIndicator;
import java.io.File;
import java.io.IOException;
import java.nio.file.Paths;
import java.util.*;
public class FileReader {
 private String path;
 private CSVReader reader;
 private List<String> linesList;
 private Set<List<String>> splitLinesSet;
 public FileReader(String path) {
 this.path = path;
 }
 public boolean readFile() {
 this.splitLinesSet = new HashSet<>();
 try {
 File file = Paths.get(path).toFile();
 reader = new CSVReaderBuilder(new java.io.FileReader(file))
 .withCSVParser(new CSVParserBuilder()
 .withSeparator('|')
 .withFieldAsNull(CSVReaderNullFieldIndicator.NEITHER).build())
 .build();
 read();
 reader.close();
 } catch (IOException e) {
 System.err.println("Error in reading CSV: " + e.getMessage());
 return false;
 }
 return true;
 }
 public Set<List<String>> getSplitLinesSet() {
 return splitLinesSet;
 }
 private void read() throws IOException {
 String[] lines;
 while ((lines = reader.readNext()) != null) {
 linesList = new ArrayList<>();
 Collections.addAll(linesList, lines);
 splitLinesSet.add(linesList);
 }
 }
}

Answer 1

I tend to advocate not passing things around which need to be closed, thus my advice is:

• inline the read method
• remove the reader field, and
• ... declare the same as a local variable
• perferably, declare that local reader variable in a try-with-resources block and throw out the explicit close()-call

Note that these changes are just about robustness and maintainability and will not affect performance or error handling.

Edit, after the comment asking for code edit. (Note: sorry, I am a newbie in the code review community, I hope this does not break any principle here.)

public class FileReader {
 private String path;
 private List<String> linesList;
 private Set<List<String>> splitLinesSet;
 public FileReader(String path) {
 this.path = path;
 }
 public boolean readFile() {
 this.splitLinesSet = new HashSet<>();
 File file = Paths.get(path).toFile();
 try (
 CSVReader reader = new CSVReaderBuilder(new java.io.FileReader(file))
 .withCSVParser(new CSVParserBuilder()
 .withSeparator('|')
 .withFieldAsNull(CSVReaderNullFieldIndicator.NEITHER).build())
 .build();
 ) {
 String[] lines;
 while ((lines = reader.readNext()) != null) {
 linesList = new ArrayList<>();
 Collections.addAll(linesList, lines);
 splitLinesSet.add(linesList);
 }
 } catch (IOException e) {
 System.err.println("Error in reading CSV: " + e.getMessage());
 return false;
 }
 return true;
 }
 public Set<List<String>> getSplitLinesSet() {
 return splitLinesSet;
 }
}

Note: this was just syntactic shuffling of lines in a text editor - I have not put this through an IDE or a compiler, but I think it shows the principles.

• mtj: @PHA : See edit, and good luck :)

Answer 2

FileReader should be avoided, because it relies on a default encoding. We should specify explicitly the encoding used.

CSVParser parser = new CSVParserBuilder().withSeparator('|').build();
try (BufferedReader br = Files.newBufferedReader(myPath, 
 StandardCharsets.UTF_8);
 CSVReader reader = new CSVReaderBuilder(br).withCSVParser(parser)
 .build()) {
...