add ExampleCsvReaderWithSpecialQuotedFieldHandling

Author: osiegmar

docs/src/content/docs/guides/Examples/quote-strategies.mdx

@@ -29,15 +29,16 @@ You may also check the corresponding
 [Javadoc](https://javadoc.io/doc/de.siegmar/fastcsv/latest/de.siegmar.fastcsv/de/siegmar/fastcsv/writer/QuoteStrategies.html)
 for more information.
 
-## Example
+## Writing fields with different quote strategies
 
 In the following example, CSV output is created using different quote strategies.
 
 <SourceExample filename="ExampleCsvWriterWithQuoteStrategy.java" highlights={[/\.quoteStrategy\(.*\)/g]}/>
 
-:::tip
-If you want to know if a field is enclosed in quotes when reading a CSV file, you may implement a
-custom callback handler. Check out the [Custom Callback handler example](/guides/examples/custom-callback-handler/)
-and especially the
-[addField() method](https://javadoc.io/doc/de.siegmar/fastcsv/latest/de.siegmar.fastcsv/de/siegmar/fastcsv/reader/CsvCallbackHandler.html).
-:::
+## Reading quoted fields
+
+To determine if a field is enclosed in quotes when reading a CSV file,
+additional work and an extra object per field are required.
+FastCSV does not support this feature out of the box, but it can be implemented using a custom callback handler.
+
+<SourceExample filename="ExampleCsvReaderWithSpecialQuotedFieldHandling.java" highlights={['QuotableFieldHandler', 'QuotableField']}/>

example/src/main/java/example/ExampleCsvReaderWithSpecialQuotedFieldHandling.java

@@ -0,0 +1,51 @@
+package example;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import de.siegmar.fastcsv.reader.AbstractBaseCsvCallbackHandler;
+import de.siegmar.fastcsv.reader.CsvReader;
+import de.siegmar.fastcsv.reader.RecordWrapper;
+
+/**
+ * Example for reading CSV data with custom handling of quoted fields.
+ */
+public class ExampleCsvReaderWithSpecialQuotedFieldHandling {
+
+    private static final String DATA = """
+        "quoted foo",unquoted foo
+        """;
+
+    public static void main(String[] args) {
+        CsvReader.builder()
+            .skipEmptyLines(false)
+            .build(new QuotableFieldHandler(), DATA)
+            .forEach(System.out::println);
+    }
+
+    static class QuotableFieldHandler extends AbstractBaseCsvCallbackHandler<List<QuotableField>> {
+
+        private final List<QuotableField> fields = new ArrayList<>();
+
+        @Override
+        protected void handleField(final int fieldIdx, final char[] buf, final int offset, final int len, final boolean quoted) {
+            final String value = new String(buf, offset, len);
+            fields.add(new QuotableField(value, quoted));
+        }
+
+        @Override
+        protected void handleBegin(final long startingLineNumber) {
+            fields.clear();
+        }
+
+        @Override
+        protected RecordWrapper<List<QuotableField>> buildRecord() {
+            return wrapRecord(List.copyOf(fields));
+        }
+
+    }
+
+    record QuotableField(String field, boolean quoted) {
+    }
+
+}