Looks like you are doing this manually rather than using a CSV reader, so your best bet is to simply read the file into a List then simply split the first line by the command , like a CSV and then check for the quotation and add them if needed. Finally, merge it back together and write it to file.
The complete code would be something like the following:
Path filePath = Path.of("csvFileTest.csv"); //Read the file List<String> lines = Files.readAllLines(filePath); //Print the header for debugging System.out.println(lines.get(0)); //Get the first line with the column labels and split the string with the comma , String[] columnHeaders = lines.get(0).split(","); //Holding value for the updated line String updatedLine = ""; //Loop the column labels for (int i = 0; i < columnHeaders.length; i++){ //Add a " to the start if it doesn't exist already if (!columnHeaders[i].startsWith("\"")) updatedLine += "\""; //Add the label updatedLine += columnHeaders[i]; //Add a " to the end if it doesn't exist already if (!columnHeaders[i].endsWith("\"")) updatedLine += "\""; //Add the , to separate the values updatedLine += ","; } //Put the updated header back into the lines array lines.set(0, updatedLine); //Print the result for debugging System.out.println(lines.get(0)); //Write back to the file Files.write(filePath, lines);
And the output is as follows, we can see that it correctly added the quotes on either side:
col1,col2,col3 "col1","col2","col3",
If you want this to work for all lines in the file then just wrap the middle section inside a loop as well and do the same for each line:
... //Loop the lines for (int l = 0; l < lines.size(); l++){ //Get the first line with the column labels and split the string with the comma , String[] line = lines.get(0).split(","); //Holding value for the updated line String updatedLine = ""; //Loop the column labels for (int i = 0; i < line.length; i++){ //Add a " to the start if it doesn't exist already if (!columnHeaders[i].startsWith("\"")) updatedLine += "\""; //Add the label updatedLine += columnHeaders[i]; //Add a " to the end if it doesn't exist already if (!columnHeaders[i].endsWith("\"")) updatedLine += "\""; //Add the , to separate the values updatedLine += ","; } //Put the updated header back into the lines array lines.set(l, updatedLine); } ...
Note: If you are using another method to read the file then don't forget to close the reader before you attempt to write back to the file.
