Initial effort at rewriting writeCSV() to use openCSV calls

Currently doesn't leave content on the OutputStreamReader.
Need to debug.

src/main/java/edu/unl/cse/csv_io/CSVReaderWriter.java

@@ -6,6 +6,8 @@ package edu.unl.cse.csv_io;
 
 import com.opencsv.CSVReaderHeaderAware;
 import com.opencsv.CSVReaderHeaderAwareBuilder;
+import com.opencsv.CSVWriterBuilder;
+import com.opencsv.ICSVWriter;
 import com.opencsv.exceptions.CsvValidationException;
 
 import java.io.*;
@@ -85,26 +87,32 @@ public class CSVReaderWriter {
     }
 
     static void placeCSVonStream(Collection<Map<String, String>> data, OutputStream outputStream) {
-        PrintStream writer = new PrintStream(outputStream);
-        Set<String> fieldNames = null;
-        int number_of_fields = 0;
+        ICSVWriter csvWriter = new CSVWriterBuilder(new OutputStreamWriter(outputStream)).build();
+        List<String[]> allLines = new LinkedList<>();
+        String[] fieldNames = getFieldNames(data);
+        int number_of_fields = fieldNames.length;
+        allLines.add(fieldNames);
         for (Map<String, String> row : data) {
+            String[] values = new String[number_of_fields];
             int field_number = 0;
-            if (fieldNames == null) {
-                fieldNames = row.keySet();
-                number_of_fields = fieldNames.size();
             for (String field : fieldNames) {
-                    writer.print(field);
-                    writer.print(++field_number < number_of_fields ? "," : "\n");
+                String value = row.get(field);
+                values[field_number++] = value != null ? value : "";
             }
+            allLines.add(values);
         }
-            field_number = 0;
-            for (String field : fieldNames) {
-                String value = row.get(field);
-                writer.print(value != null ? value : "");
-                writer.print(++field_number < number_of_fields ? "," : "\n");
+        csvWriter.writeAll(allLines, false);
     }
+
+    private static String[] getFieldNames(Collection<Map<String, String>> data) {
+        Set<String> fieldNames = new HashSet<>();
+        for (Map<String, String> row : data) {
+            fieldNames.addAll(row.keySet());
         }
+        List<String> fieldList = new ArrayList<>(fieldNames);
+        String[] fieldArray = new String[fieldList.size()];
+        fieldArray = fieldList.toArray(fieldArray);
+        return fieldArray;
     }
 
     /* LEGACY METHODS */