Tightened the design a little.

- Replaced Iterable with Collection in signatures
- Moved exception-handling code closer to exception sources

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

@@ -14,6 +14,7 @@ import java.util.*;
 
 @SuppressWarnings("unused")
 public class CSVReaderWriter {
+
     @SuppressWarnings("WeakerAccess")
     public static Set<Map<String, String>> readCSVasSet(String filename) {
         Set<Map<String, String>> csvSet = null;
@@ -22,13 +23,8 @@ public class CSVReaderWriter {
             csvSet = (Set<Map<String, String>>) parseCSV(inputStreamReader, new HashSet<>());
         } catch (NullPointerException nullPointerException) {
             System.err.println("Check spelling of file " + filename + ".");
-            System.exit(1);
         } catch (IOException ioException) {
             System.err.println("Error loading " + filename + ".  " + ioException);
-            System.exit(1);
-        } catch (CsvValidationException csvValidationException) {
-            System.err.println("Could not validate a line in " + filename + ".  " + csvValidationException);
-            System.exit(1);
         }
         return csvSet;
     }
@@ -40,20 +36,14 @@ public class CSVReaderWriter {
             csvList = (List<Map<String, String>>) parseCSV(inputStreamReader, new LinkedList<>());
         } catch (NullPointerException nullPointerException) {
             System.err.println("Check spelling of file " + filename + ".");
-            System.exit(1);
         } catch (IOException ioException) {
             System.err.println("Error loading " + filename + ".  " + ioException);
-            System.exit(1);
-        } catch (CsvValidationException csvValidationException) {
-            System.err.println("Could not validate a line in " + filename + ".  " + csvValidationException);
-            System.exit(1);
         }
         return csvList;
     }
 
     private static Collection<Map<String, String>> parseCSV(InputStreamReader inputStreamReader,
-                                                            Collection<Map<String, String>> destination)
-            throws IOException, CsvValidationException {
+                                                            Collection<Map<String, String>> destination) {
         Map<String, String> line;
         try {
             CSVReaderHeaderAware csvReader = new CSVReaderHeaderAwareBuilder(inputStreamReader).build();
@@ -62,32 +52,17 @@ public class CSVReaderWriter {
             }
         } catch (NullPointerException ignored) {
             // CSVReaderHeaderAwareBuilder.build() throws NullPointerException if inputStreamReader is empty
-        }
-        return destination;
-    }
-
-    /* LEGACY METHODS */
-    @SuppressWarnings("WeakerAccess")
-    public static Set<Map<String, String>> readCSV(String filename) {
-        return readCSVasSet(filename);
-    }
-/*
-    public static Set<Map<String, String>> readCSV(String filename) {
-        Set<Map<String, String>> csvSet = null;
-        ClassLoader classLoader = CSVReaderWriter.class.getClassLoader();
-        try (InputStream inputStream = classLoader.getResourceAsStream("csv/" + filename)) {
-            csvSet = parseCSV(inputStream);
         } catch (IOException ioException) {
-            System.err.println("Error loading " + filename + ".  " + ioException);
+            System.err.println("Error reading CSV file.  " + ioException);
+        } catch (CsvValidationException csvValidationException) {
+            System.err.println("Could not validate a line in CSV file.  " + csvValidationException);
         }
-        return csvSet;
+        return destination;
     }
-*/
 
     // I'd like to replace this with something that uses openCSV, but it works, and openCSV doesn't seem to have
     // writers that take map<string,string>
-    @SuppressWarnings("WeakerAccess")
-    public static boolean writeCSV(String filename, Iterable<Map<String, String>> data) {
+    public static boolean writeCSV(String filename, Collection<Map<String, String>> data) {
         boolean wroteFile = true;
         ClassLoader classLoader = CSVReaderWriter.class.getClassLoader();
         URL resource = classLoader.getResource("csv/" + filename);
@@ -109,45 +84,7 @@ public class CSVReaderWriter {
         return wroteFile;
     }
 
-
-    static Set<Map<String, String>> parseCSV(InputStream inputStream) throws IOException {
-        try {
-            return (Set<Map<String, String>>) parseCSV(new InputStreamReader(inputStream), new HashSet<>());
-        } catch (CsvValidationException csvValidationException) {
-            csvValidationException.printStackTrace();
-            return null;
-        }
-    }
-/*
-    static Set<Map<String, String>> parseCSV(InputStream inputStream) throws IOException {
-        Set<Map<String, String>> csvSet = new HashSet<>();
-        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
-        String line;
-        List<String> fieldNames = new ArrayList<>();
-        boolean header = true;
-        while ((line = reader.readLine()) != null) {
-            String[] elements = line.split(DELIMTER);
-            if (header) {
-                if (elements[0].charAt(0) == BYTE_ORDER_MARK) {
-                    elements[0] = elements[0].substring(1);     // remove text-encoding character sometimes added by
-                    // Excel
-                }
-                fieldNames.addAll(Arrays.asList(elements));
-                header = false;
-            } else {
-                Map<String, String> row = new HashMap<>();
-                int column = 0;
-                for (String element : elements) {
-                    row.put(fieldNames.get(column++), element);
-                }
-                csvSet.add(row);
-            }
-        }
-        return csvSet;
-    }
-*/
-
-    static void placeCSVonStream(Iterable<Map<String, String>> data, OutputStream outputStream) {
+    static void placeCSVonStream(Collection<Map<String, String>> data, OutputStream outputStream) {
         PrintStream writer = new PrintStream(outputStream);
         Set<String> fieldNames = null;
         int number_of_fields = 0;
@@ -170,9 +107,20 @@ public class CSVReaderWriter {
         }
     }
 
+    /* LEGACY METHODS */
+    public static Set<Map<String, String>> readCSV(String filename) {
+        return readCSVasSet(filename);
+    }
+
+    static Set<Map<String, String>> parseCSV(InputStream inputStream) {
+        return (Set<Map<String, String>>) parseCSV(new InputStreamReader(inputStream), new HashSet<>());
+    }
+    
+/*
     public static void main(String[] args) {
         Set<Map<String, String>> demo = readCSV("demo.csv");
         boolean success = writeCSV("out.csv", demo);
         System.out.println(success ? "Wrote file!" : "Didn't write file");
     }
+*/
 }

src/main/resources/csv/demo.csv

-A,B,C,D
+A,B,C,D
 larry,curly,moe,
-one,two,,three
-four,,five,six
-7,8,9,
-,alpha,beta,gamma
\ No newline at end of file

src/test/java/edu/unl/cse/csv_io/CSVReaderWriterTest.java

@@ -49,12 +49,8 @@ public class CSVReaderWriterTest {
         String[][] data = {headers, row};
         // Output
         placeCSVStringOnInputStream(data);
-        Set<Map<String, String>> result = null;
-        try {
+        Set<Map<String, String>> result;
         result = CSVReaderWriter.parseCSV(inputStream);
-        } catch (IOException ignored) {
-            fail();
-        }
         // Oracle -- Header
         Set<String> expectedKeys = new HashSet<>(Arrays.asList(headers));
         // Oracle -- Rows
@@ -77,12 +73,8 @@ public class CSVReaderWriterTest {
         String[][] data = {headers, rows[0], rows[1]};
         // Output
         placeCSVStringOnInputStream(data);
-        Set<Map<String, String>> result = null;
-        try {
+        Set<Map<String, String>> result;
         result = CSVReaderWriter.parseCSV(inputStream);
-        } catch (IOException ignored) {
-            fail();
-        }
         // Oracle -- Header
         Set<String> expectedKeys = new HashSet<>(Arrays.asList(headers));
         // Oracle -- Rows
@@ -109,12 +101,8 @@ public class CSVReaderWriterTest {
         String[][] data = {headers};
         // Output
         placeCSVStringOnInputStream(data);
-        Set<Map<String, String>> result = null;
-        try {
+        Set<Map<String, String>> result;
         result = CSVReaderWriter.parseCSV(inputStream);
-        } catch (IOException ignored) {
-            fail();
-        }
         // Oracle
         int expectedResultSize = 0;
         // Compare
@@ -128,12 +116,8 @@ public class CSVReaderWriterTest {
         String[][] data = {};
         // Output
         placeCSVStringOnInputStream(data);
-        Set<Map<String, String>> result = null;
-        try {
+        Set<Map<String, String>> result;
         result = CSVReaderWriter.parseCSV(inputStream);
-        } catch (IOException ignored) {
-            fail();
-        }
         // Oracle
         int expectedResultSize = 0;
         // Compare