fix null pointer when value is null - Java bug

Author: kuros

pom.xml

@@ -12,7 +12,7 @@
 
     <groupId>in.kuros</groupId>
     <artifactId>jFirebase</artifactId>
-    <version>0.6.6</version>
+    <version>0.6.7</version>
 
 
     <description>This project aims at building a wrapper over nosql technologies - Firebase</description>

src/main/java/in/kuros/jfirebase/metadata/UpdateAttribute.java

@@ -1,6 +1,7 @@
 package in.kuros.jfirebase.metadata;
 
 import com.google.common.collect.Lists;
+import in.kuros.jfirebase.util.CustomCollectors;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -85,7 +86,7 @@ public interface Helper {
 
         static <T> Map<String, ?> getValuePaths(UpdateAttribute<T> updateAttribute) {
             return updateAttribute.valuePaths.stream()
-                    .collect(Collectors.toMap(vp -> vp.getPath()[0], ValuePath::getValue));
+                    .collect(CustomCollectors.toMap(vp -> vp.getPath()[0], ValuePath::getValue));
         }
 
         static <T> Class<T> getDeclaringClass(UpdateAttribute<T> updateAttribute) {

src/main/java/in/kuros/jfirebase/util/CustomCollectors.java

@@ -0,0 +1,82 @@
+package in.kuros.jfirebase.util;
+
+import com.google.common.collect.Sets;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import lombok.RequiredArgsConstructor;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public final class CustomCollectors {
+
+    public static <T, K, V> Collector<T, Map<K, V>, Map<K, V>> toMap(final Function<? super T, K> keyMapper,
+                                                                     final Function<T, V> valueMapper) {
+        return new CustomCollectorImpl<>(HashMap::new,
+                (kvMap, t) -> kvMap.put(keyMapper.apply(t), valueMapper.apply(t)),
+                (kvMap, kvMap2) -> {
+                    kvMap.putAll(kvMap2);
+                    return kvMap;
+                },
+                Function.identity(),
+                Collector.Characteristics.IDENTITY_FINISH);
+    }
+
+    public static <T, K, V> Collector<T, Map<K, V>, Map<K, V>> toMap(final Function<? super T, K> keyMapper,
+                                                                     final Function<T, V> valueMapper,
+                                                                     final BinaryOperator<V> mergeFunction) {
+        return new CustomCollectorImpl<>(HashMap::new,
+                (kvMap, t) -> {
+                    final K key = keyMapper.apply(t);
+                    kvMap.put(key, mergeFunction.apply(kvMap.get(key), valueMapper.apply(t)));
+                },
+                (kvMap, kvMap2) -> {
+                    kvMap.putAll(kvMap2);
+                    return kvMap;
+                },
+                Function.identity(),
+                Collector.Characteristics.IDENTITY_FINISH);
+    }
+
+    @RequiredArgsConstructor
+    static class CustomCollectorImpl<T, A, R> implements Collector<T, A, R> {
+
+        private final Supplier<A> supplier;
+        private final BiConsumer<A, T> accumulator;
+        private final BinaryOperator<A> combiner;
+        private final Function<A, R> finisher;
+        private final Characteristics characteristics;
+
+        @Override
+        public Supplier<A> supplier() {
+            return supplier;
+        }
+
+        @Override
+        public BiConsumer<A, T> accumulator() {
+            return accumulator;
+        }
+
+        @Override
+        public BinaryOperator<A> combiner() {
+            return combiner;
+        }
+
+        @Override
+        public Function<A, R> finisher() {
+            return finisher;
+        }
+
+        @Override
+        public Set<Characteristics> characteristics() {
+            return Sets.newHashSet(characteristics);
+        }
+    }
+}