java - How to escape comma and double quote at same time for CSV file?

Question

I am writing a Java app to export data from Oracle to csv file

Unfortunately the content of data may quite tricky. Still comma is the deliminator, but some data on a row could be like this:

| ID    |   FN    |   LN   |  AGE   |  COMMENT                   |
|----------------------------------------------------------------|
| 123   |  John   |  Smith |   39   | I said "Hey, I am 5'10"."  |
|----------------------------------------------------------------|

so this is one of the string on the comment column:

I said "Hey, I am 5'10"."

No kidding, I need to show above comment without compromise in excel or open office from a CSV file generated by Java, and of course cannot mess up other regular escaping situation(i.e. regular double quotes, and regular comma within a tuple). I know regular expression is powerful but how can we achieve the goal with such complicated situation?

Answer 1

There are several libraries. Here are two examples:

---

❐ Apache Commons Lang

Apache Commons Lang includes a special class to escape or unescape strings (CSV, EcmaScript, HTML, Java, Json, XML): org.apache.commons.lang3.StringEscapeUtils.

• Escape to CSV

  String escaped = StringEscapeUtils
      .escapeCsv("I said "Hey, I am 5'10".""); // I said "Hey, I am 5'10"."
  
  System.out.println(escaped); // "I said ""Hey, I am 5'10""."""
  

• Unescape from CSV

  String unescaped = StringEscapeUtils
      .unescapeCsv(""I said ""Hey, I am 5'10"".""""); // "I said ""Hey, I am 5'10""."""
  
  System.out.println(unescaped); // I said "Hey, I am 5'10"."
  

_{* You can download it from here.}

---

❐ OpenCSV

If you use OpenCSV, you will not need to worry about escape or unescape, only for write or read the content.

• Writing file:

  FileOutputStream fos = new FileOutputStream("awesomefile.csv"); 
  OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
  CSVWriter writer = new CSVWriter(osw);
  ...
  String[] row = {
      "123", 
      "John", 
      "Smith", 
      "39", 
      "I said "Hey, I am 5'10".""
  };
  writer.writeNext(row);
  ...
  writer.close();
  osw.close();
  os.close();
  

• Reading file:

  FileInputStream fis = new FileInputStream("awesomefile.csv"); 
  InputStreamReader isr = new InputStreamReader(fis, "UTF-8");
  CSVReader reader = new CSVReader(isr);
  
  for (String[] row; (row = reader.readNext()) != null;) {
      System.out.println(Arrays.toString(row));
  }
  
  reader.close();
  isr.close();
  fis.close();
  

_{* You can download it from here.}