Fix display bug for keyword groups with empty keywords (#5347)

Fix display bug for keyword groups with empty keywords

Author: koppor

CHANGELOG.md

@@ -25,6 +25,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - After assigning an entry to a group, the item count is now properly colored to reflect the new membership of the entry. [#3112](https://github.com/JabRef/jabref/issues/3112)
 - The group panel is now properly updated when switching between libraries (or when closing/opening one). [#3142](https://github.com/JabRef/jabref/issues/3142)
 - We fixed an error where the number of matched entries shown in the group pane was not updated correctly. [#4441](https://github.com/JabRef/jabref/issues/4441)
+- We fixed an issue where empty keywords lead to a strange display of automatic keyword groups. [#5333](https://github.com/JabRef/jabref/issues/5333)
 - We fixed an error where the default color of a new group was white instead of dark gray. [#4868](https://github.com/JabRef/jabref/issues/4868)
 - We fixed an error mentioning "javafx.controls/com.sun.javafx.scene.control" that was thrown when interacting with the toolbar.
 - We fixed an error where a cleared search was restored after switching libraries. [#4846](https://github.com/JabRef/jabref/issues/4846) 

src/main/java/org/jabref/model/groups/AutomaticKeywordGroup.java

@@ -9,6 +9,7 @@
 import org.jabref.model.entry.Keyword;
 import org.jabref.model.entry.KeywordList;
 import org.jabref.model.entry.field.Field;
+import org.jabref.model.strings.StringUtil;
 import org.jabref.model.util.OptionalUtil;
 
 public class AutomaticKeywordGroup extends AutomaticGroup {
@@ -62,11 +63,12 @@ public int hashCode() {
     @Override
     public Set<GroupTreeNode> createSubgroups(BibEntry entry) {
         Optional<KeywordList> keywordList = entry.getLatexFreeField(field)
-                .map(fieldValue -> KeywordList.parse(fieldValue, keywordDelimiter));
+                                                 .map(fieldValue -> KeywordList.parse(fieldValue, keywordDelimiter));
         return OptionalUtil.toStream(keywordList)
-                .flatMap(KeywordList::stream)
-                .map(this::createGroup)
-                .collect(Collectors.toSet());
+                           .flatMap(KeywordList::stream)
+                           .filter(keyword -> StringUtil.isNotBlank(keyword.get()))
+                           .map(this::createGroup)
+                           .collect(Collectors.toSet());
     }
 
     private GroupTreeNode createGroup(Keyword keywordChain) {
@@ -80,8 +82,8 @@ private GroupTreeNode createGroup(Keyword keywordChain) {
                 true);
         GroupTreeNode root = new GroupTreeNode(rootGroup);
         keywordChain.getChild()
-                .map(this::createGroup)
-                .ifPresent(root::addChild);
+                    .map(this::createGroup)
+                    .ifPresent(root::addChild);
         return root;
     }
 }

src/test/java/org/jabref/model/groups/AutomaticKeywordGroupTest.java

@@ -10,10 +10,10 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-public class AutomaticKeywordGroupTest {
+class AutomaticKeywordGroupTest {
 
     @Test
-    public void createSubgroupsForTwoKeywords() throws Exception {
+    void createSubgroupsForTwoKeywords() throws Exception {
         AutomaticKeywordGroup keywordsGroup = new AutomaticKeywordGroup("Keywords", GroupHierarchyType.INDEPENDENT, StandardField.KEYWORDS, ',', '>');
         BibEntry entry = new BibEntry().withField(StandardField.KEYWORDS, "A, B");
 
@@ -22,4 +22,15 @@ public void createSubgroupsForTwoKeywords() throws Exception {
         expected.add(GroupTreeNode.fromGroup(new WordKeywordGroup("B", GroupHierarchyType.INCLUDING, StandardField.KEYWORDS, "B", true, ',', true)));
         assertEquals(expected, keywordsGroup.createSubgroups(entry));
     }
+
+    @Test
+    void createSubgroupsIgnoresEmptyKeyword() throws Exception {
+        AutomaticKeywordGroup keywordsGroup = new AutomaticKeywordGroup("Keywords", GroupHierarchyType.INDEPENDENT, StandardField.KEYWORDS, ',', '>');
+        BibEntry entry = new BibEntry().withField(StandardField.KEYWORDS, "A, ,B");
+
+        Set<GroupTreeNode> expected = new HashSet<>();
+        expected.add(GroupTreeNode.fromGroup(new WordKeywordGroup("A", GroupHierarchyType.INCLUDING, StandardField.KEYWORDS, "A", true, ',', true)));
+        expected.add(GroupTreeNode.fromGroup(new WordKeywordGroup("B", GroupHierarchyType.INCLUDING, StandardField.KEYWORDS, "B", true, ',', true)));
+        assertEquals(expected, keywordsGroup.createSubgroups(entry));
+    }
 }