From 9679506278fbf3e76c74a8af09731760ebd45be5 Mon Sep 17 00:00:00 2001
From: Mark Paluch <mpaluch@pivotal.io>
Date: Wed, 26 Apr 2017 13:59:35 +0200
Subject: [PATCH] DATACASS-439 - Polishing.

Refactor static converter instances to enum types with a single instance.
---
 .../core/converter/ResultSetToListConverter.java      |  2 +-
 .../cassandra/core/converter/RowToArrayConverter.java | 11 ++++++++---
 .../cassandra/core/converter/RowToListConverter.java  |  4 ++--
 .../cassandra/core/converter/RowToMapConverter.java   |  4 ++--
 4 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/ResultSetToListConverter.java b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/ResultSetToListConverter.java
index 2e2c3bf1d..bb861a69f 100644
--- a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/ResultSetToListConverter.java
+++ b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/ResultSetToListConverter.java
@@ -38,7 +38,7 @@ public class ResultSetToListConverter implements Converter<ResultSet, List<Map<S
 	 * Create a new {@link ResultSetToListConverter} using a default {@link RowToMapConverter}.
 	 */
 	public ResultSetToListConverter() {
-		this(new RowToMapConverter());
+		this(RowToMapConverter.INSTANCE);
 	}
 
 	/**
diff --git a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToArrayConverter.java b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToArrayConverter.java
index ba4685ca5..b67ac24a1 100644
--- a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToArrayConverter.java
+++ b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToArrayConverter.java
@@ -21,9 +21,14 @@ import org.springframework.core.convert.converter.Converter;
 
 import com.datastax.driver.core.Row;
 
-public class RowToArrayConverter implements Converter<Row, Object[]> {
+/**
+ * Converter to convert {@link Row} to {@link Object} array.
+ *
+ * @author Mark Paluch
+ */
+public enum RowToArrayConverter implements Converter<Row, Object[]> {
 
-	protected RowToListConverter delegate = new RowToListConverter();
+	INSTANCE;
 
 	/* (non-Javadoc)
 	 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
@@ -31,7 +36,7 @@ public class RowToArrayConverter implements Converter<Row, Object[]> {
 	@Override
 	public Object[] convert(Row row) {
 
-		List<Object> list = delegate.convert(row);
+		List<Object> list = RowToListConverter.INSTANCE.convert(row);
 		return list == null ? null : list.toArray();
 	}
 }
diff --git a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToListConverter.java b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToListConverter.java
index fbea029e2..22c2d9de1 100644
--- a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToListConverter.java
+++ b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToListConverter.java
@@ -34,9 +34,9 @@ import com.datastax.driver.core.Row;
  * @author Antoine Toulme
  */
 @ReadingConverter
-public class RowToListConverter implements Converter<Row, List<Object>> {
+public enum RowToListConverter implements Converter<Row, List<Object>> {
 
-	public final static RowToListConverter INSTANCE = new RowToListConverter();
+	INSTANCE;
 
 	/* (non-Javadoc)
 	 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)
diff --git a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToMapConverter.java b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToMapConverter.java
index b8ed7e24e..8d5d83a28 100644
--- a/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToMapConverter.java
+++ b/spring-cql/src/main/java/org/springframework/cassandra/core/converter/RowToMapConverter.java
@@ -34,9 +34,9 @@ import com.datastax.driver.core.Row;
  * @author Antoine Toulme
  */
 @ReadingConverter
-public class RowToMapConverter implements Converter<Row, Map<String, Object>> {
+public enum RowToMapConverter implements Converter<Row, Map<String, Object>> {
 
-	public final static RowToMapConverter INSTANCE = new RowToMapConverter();
+	INSTANCE;
 
 	/* (non-Javadoc)
 	 * @see org.springframework.core.convert.converter.Converter#convert(java.lang.Object)