All working, able to be built to .jar

src/main/java/MatchingFileWriter.java

@@ -0,0 +1,52 @@
+import org.apache.commons.csv.CSVFormat;
+import org.apache.commons.csv.CSVPrinter;
+
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.List;
+
+
+public class MatchingFileWriter {
+
+    private String filename;
+    private List<String> comments;
+    private List<String> headers;
+    private List<List<String>> results;
+
+    public MatchingFileWriter(String filename, List<String> comments, List<String> headers, List<List<String>> results){
+        if(!filename.matches(".*\\.csv")){
+            filename = filename + ".csv";
+        }
+        this.filename = filename;
+        this.comments = comments;
+        this.headers = headers;
+        this.results = results;
+    }
+
+    public void writeResultsToFile(){
+        String[] headerStrings = new String[headers.size()];
+        for(int i = 0; i < headers.size(); i++){
+            headerStrings[i] = headers.get(i);
+        }
+        CSVFormat resultsFileFormat = CSVFormat.Builder.create()
+                .setCommentMarker('#')
+                //.setHeader(headerStrings)
+                .build();
+        try(BufferedWriter writer = Files.newBufferedWriter(Path.of(filename), StandardOpenOption.CREATE_NEW);
+            CSVPrinter printer = new CSVPrinter(writer, resultsFileFormat);
+        ){
+            for(String comment: comments){
+                printer.printComment(comment);
+            }
+            results.add(0, headers);
+            printer.printRecords(results);
+
+        } catch(IOException ex){
+            System.out.println("Could not make new file named "+filename);
+            System.err.println(ex);
+        }
+    }
+}