Add support for trailing text after the closing quote, for Excel compatibility.

src/main/java/org/apache/commons/csv/CSVFormat.java

@@ -208,6 +208,8 @@ public final class CSVFormat implements Serializable {
 
         private boolean allowMissingColumnNames;
 
+        private boolean allowTrailingText;
+
         private boolean autoFlush;
 
         private Character commentMarker;
@@ -264,6 +266,7 @@ public final class CSVFormat implements Serializable {
             this.autoFlush = csvFormat.autoFlush;
             this.quotedNullString = csvFormat.quotedNullString;
             this.duplicateHeaderMode = csvFormat.duplicateHeaderMode;
+            this.allowTrailingText = csvFormat.allowTrailingText;
         }
 
         /**
@@ -301,6 +304,20 @@ public final class CSVFormat implements Serializable {
             return this;
         }
 
+        /**
+         * Sets whether to allow trailing text in a quoted field, after the closing quote.
+         *
+         * @param allowTrailingText the trailing text behavior, {@code true} to append that text to the field contents, {@code false} to throw
+         *        an {@link IOException}.
+         *
+         * @return This instance.
+         * @since 1.10.0
+         */
+        public Builder setAllowTrailingText(final boolean allowTrailingText) {
+            this.allowTrailingText = allowTrailingText;
+            return this;
+        }
+
         /**
          * Sets whether to flush on close.
          *
@@ -810,7 +827,7 @@ public final class CSVFormat implements Serializable {
      * @see Predefined#Default
      */
     public static final CSVFormat DEFAULT = new CSVFormat(COMMA, DOUBLE_QUOTE_CHAR, null, null, null, false, true, CRLF, null, null, null, false, false, false,
-            false, false, false, DuplicateHeaderMode.ALLOW_ALL);
+            false, false, false, DuplicateHeaderMode.ALLOW_ALL, false);
 
     /**
      * Excel file format (using a comma as the value delimiter). Note that the actual value delimiter used by Excel is locale dependent, it might be necessary
@@ -834,6 +851,7 @@ public final class CSVFormat implements Serializable {
      * <li>{@code setIgnoreEmptyLines(false)}</li>
      * <li>{@code setAllowMissingColumnNames(true)}</li>
      * <li>{@code setDuplicateHeaderMode(DuplicateHeaderMode.ALLOW_ALL)}</li>
+     * <li>{@code setAllowTrailingText(true)}</li>
      * </ul>
      * <p>
      * Note: This is currently like {@link #RFC4180} plus {@link Builder#setAllowMissingColumnNames(boolean) Builder#setAllowMissingColumnNames(true)} and
@@ -846,6 +864,7 @@ public final class CSVFormat implements Serializable {
     public static final CSVFormat EXCEL = DEFAULT.builder()
             .setIgnoreEmptyLines(false)
             .setAllowMissingColumnNames(true)
+            .setAllowTrailingText(true)
             .build();
     // @formatter:on
 
@@ -1268,7 +1287,7 @@ public final class CSVFormat implements Serializable {
      */
     public static CSVFormat newFormat(final char delimiter) {
         return new CSVFormat(String.valueOf(delimiter), null, null, null, null, false, false, null, null, null, null, false, false, false, false, false, false,
-                DuplicateHeaderMode.ALLOW_ALL);
+                DuplicateHeaderMode.ALLOW_ALL, false);
     }
 
     static String[] toStringArray(final Object[] values) {
@@ -1312,6 +1331,8 @@ public final class CSVFormat implements Serializable {
 
     private final boolean allowMissingColumnNames;
 
+    private final boolean allowTrailingText;
+
     private final boolean autoFlush;
 
     private final Character commentMarker; // null if commenting is disabled
@@ -1366,6 +1387,7 @@ public final class CSVFormat implements Serializable {
         this.autoFlush = builder.autoFlush;
         this.quotedNullString = builder.quotedNullString;
         this.duplicateHeaderMode = builder.duplicateHeaderMode;
+        this.allowTrailingText = builder.allowTrailingText;
         validate();
     }
 
@@ -1396,7 +1418,7 @@ public final class CSVFormat implements Serializable {
             final boolean ignoreSurroundingSpaces, final boolean ignoreEmptyLines, final String recordSeparator, final String nullString,
             final Object[] headerComments, final String[] header, final boolean skipHeaderRecord, final boolean allowMissingColumnNames,
             final boolean ignoreHeaderCase, final boolean trim, final boolean trailingDelimiter, final boolean autoFlush,
-            final DuplicateHeaderMode duplicateHeaderMode) {
+            final DuplicateHeaderMode duplicateHeaderMode, final boolean allowTrailingText) {
         this.delimiter = delimiter;
         this.quoteCharacter = quoteChar;
         this.quoteMode = quoteMode;
@@ -1416,6 +1438,7 @@ public final class CSVFormat implements Serializable {
         this.autoFlush = autoFlush;
         this.quotedNullString = quoteCharacter + nullString + quoteCharacter;
         this.duplicateHeaderMode = duplicateHeaderMode;
+        this.allowTrailingText = allowTrailingText;
         validate();
     }
 
@@ -1469,7 +1492,8 @@ public final class CSVFormat implements Serializable {
                 ignoreHeaderCase == other.ignoreHeaderCase && ignoreSurroundingSpaces == other.ignoreSurroundingSpaces &&
                 Objects.equals(nullString, other.nullString) && Objects.equals(quoteCharacter, other.quoteCharacter) && quoteMode == other.quoteMode &&
                 Objects.equals(quotedNullString, other.quotedNullString) && Objects.equals(recordSeparator, other.recordSeparator) &&
-                skipHeaderRecord == other.skipHeaderRecord && trailingDelimiter == other.trailingDelimiter && trim == other.trim;
+                skipHeaderRecord == other.skipHeaderRecord && trailingDelimiter == other.trailingDelimiter && trim == other.trim &&
+                allowTrailingText == other.allowTrailingText;
     }
 
     /**
@@ -1512,6 +1536,16 @@ public final class CSVFormat implements Serializable {
         return allowMissingColumnNames;
     }
 
+    /**
+     * Gets whether quoted fields allow trailing text after the closing quote.
+     *
+     * @return {@code true} if allowed, {@code false} to throw an {@link IOException}.
+     * @since 1.10.0
+     */
+    public boolean getAllowTrailingText() {
+        return allowTrailingText;
+    }
+
     /**
      * Gets whether to flush on close.
      *
@@ -1692,9 +1726,9 @@ public final class CSVFormat implements Serializable {
         int result = 1;
         result = prime * result + Arrays.hashCode(headers);
         result = prime * result + Arrays.hashCode(headerComments);
-        return prime * result + Objects.hash(duplicateHeaderMode, allowMissingColumnNames, autoFlush, commentMarker, delimiter, escapeCharacter,
+        return prime * result + Objects.hash(duplicateHeaderMode, allowMissingColumnNames, allowTrailingText, autoFlush, commentMarker, delimiter,
-                ignoreEmptyLines, ignoreHeaderCase, ignoreSurroundingSpaces, nullString, quoteCharacter, quoteMode, quotedNullString, recordSeparator,
+                escapeCharacter, ignoreEmptyLines, ignoreHeaderCase, ignoreSurroundingSpaces, nullString, quoteCharacter, quoteMode, quotedNullString,
-                skipHeaderRecord, trailingDelimiter, trim);
+                recordSeparator, skipHeaderRecord, trailingDelimiter, trim);
     }
 
     /**

src/main/java/org/apache/commons/csv/Lexer.java

@@ -57,6 +57,7 @@ final class Lexer implements Closeable {
 
     private final boolean ignoreSurroundingSpaces;
     private final boolean ignoreEmptyLines;
+    private final boolean allowTrailingText;
 
     /** The input stream */
     private final ExtendedBufferedReader reader;
@@ -72,6 +73,7 @@ final class Lexer implements Closeable {
         this.commentStart = mapNullToDisabled(format.getCommentMarker());
         this.ignoreSurroundingSpaces = format.getIgnoreSurroundingSpaces();
         this.ignoreEmptyLines = format.getIgnoreEmptyLines();
+        this.allowTrailingText = format.getAllowTrailingText();
         this.delimiterBuf = new char[delimiter.length - 1];
         this.escapeDelimiterBuf = new char[2 * delimiter.length - 1];
     }
@@ -364,10 +366,14 @@ final class Lexer implements Closeable {
                             token.type = EORECORD;
                             return token;
                         }
-                        if (!Character.isWhitespace((char)c)) {
+                        if (allowTrailingText) {
-                            // error invalid char between token and next delimiter
+                            token.content.append((char) c);
-                            throw new IOException("(line " + getCurrentLineNumber() +
+                        } else {
-                                    ") invalid char between encapsulated token and delimiter");
+                            if (!Character.isWhitespace((char)c)) {
+                                // error invalid char between token and next delimiter
+                                throw new IOException("(line " + getCurrentLineNumber() +
+                                        ") invalid char between encapsulated token and delimiter");
+                            }
                         }
                     }
                 }

src/test/java/org/apache/commons/csv/LexerTest.java

@@ -431,4 +431,17 @@ public class LexerTest {
         lexer.trimTrailingSpaces(buffer);
         assertThat(lexer.nextToken(new Token()), matches(EOF, ""));
     }
+
+    @Test
+    public void testTrailingTextAfterQuote() throws Exception {
+        final String code = "\"a\" b,\"a\" \" b,\"a\" b \"\"";
+        try (final Lexer parser = createLexer(code, CSVFormat.Builder.create().setAllowTrailingText(true).build())) {
+            assertThat(parser.nextToken(new Token()), matches(TOKEN, "a b"));
+            assertThat(parser.nextToken(new Token()), matches(TOKEN, "a \" b"));
+            assertThat(parser.nextToken(new Token()), matches(EOF, "a b \"\""));
+        }
+        try (final Lexer parser = createLexer(code, CSVFormat.Builder.create().setAllowTrailingText(false).build())) {
+            assertThrows(IOException.class, () -> lexer.nextToken(new Token()));
+        }
+    }
 }