From f3110de1306659b6cd70a318a1070a28fefc680e Mon Sep 17 00:00:00 2001
From: qza <kokovic.zoran@gmail.com>
Date: Thu, 2 Jun 2016 07:32:48 +0200
Subject: [PATCH] #355 handle case when there are no child elements for the
 given key

---
 .../com/iluwatar/abstractdocument/AbstractDocument.java   | 7 ++++---
 .../iluwatar/abstractdocument/AbstractDocumentTest.java   | 8 +++++++-
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/abstract-document/src/main/java/com/iluwatar/abstractdocument/AbstractDocument.java b/abstract-document/src/main/java/com/iluwatar/abstractdocument/AbstractDocument.java
index c3f8e2a4b..f5ef69e3c 100644
--- a/abstract-document/src/main/java/com/iluwatar/abstractdocument/AbstractDocument.java
+++ b/abstract-document/src/main/java/com/iluwatar/abstractdocument/AbstractDocument.java
@@ -3,6 +3,7 @@ package com.iluwatar.abstractdocument;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
@@ -28,11 +29,11 @@ public abstract class AbstractDocument implements Document {
 
     @Override
     public <T> Stream<T> children(String key, Function<Map<String, Object>, T> constructor) {
-        return Stream.of(get(key))
+        Optional<List<Map<String, Object>>> any = Stream.of(get(key))
                 .filter(el -> el != null)
                 .map(el -> (List<Map<String, Object>>) el)
-                .findAny().get().stream()
-                .map(constructor);
+                .findAny();
+        return any.isPresent() ? any.get().stream().map(constructor) : Stream.empty();
     }
 
     @Override
diff --git a/abstract-document/src/test/java/com/iluwatar/abstractdocument/AbstractDocumentTest.java b/abstract-document/src/test/java/com/iluwatar/abstractdocument/AbstractDocumentTest.java
index 43585d853..baf872e4f 100644
--- a/abstract-document/src/test/java/com/iluwatar/abstractdocument/AbstractDocumentTest.java
+++ b/abstract-document/src/test/java/com/iluwatar/abstractdocument/AbstractDocumentTest.java
@@ -29,7 +29,6 @@ public class AbstractDocumentTest {
     public void shouldPutAndGetValue() {
         document.put(KEY, VALUE);
         assertEquals(VALUE, document.get(KEY));
-        System.out.println(document);
     }
 
     @Test
@@ -45,4 +44,11 @@ public class AbstractDocumentTest {
         assertEquals(2, childrenStream.count());
     }
 
+    @Test
+    public void shouldRetrieveEmptyStreamForNonExistinChildren() {
+        Stream<DocumentImplementation> children = document.children(KEY, DocumentImplementation::new);
+        assertNotNull(children);
+        assertEquals(0, children.count());
+    }
+
 }