add meaningful names in DublinCoreExtractor and use StringUtils.isNul…

…lOrEmpty

src/main/java/org/jabref/logic/xmp/DublinCoreExtractor.java

@@ -15,7 +15,9 @@
 import org.jabref.model.entry.BibEntry;
 import org.jabref.model.entry.FieldName;
 import org.jabref.model.entry.Month;
+import org.jabref.model.strings.StringUtil;
 
+import com.microsoft.applicationinsights.agent.internal.common.StringUtils;
 import org.apache.xmpbox.DateConverter;
 import org.apache.xmpbox.schema.DublinCoreSchema;
 
@@ -69,16 +71,16 @@ private void extractYearAndMonth() {
  List<String> dates = dcSchema.getUnqualifiedSequenceValueList("date");
  if ((dates != null) && !dates.isEmpty()) {
  String date = dates.get(0).trim();
- Calendar c = null;
+ Calendar calender = null;
  try {
- c = DateConverter.toCalendar(date);
+ calender = DateConverter.toCalendar(date);
  } catch (IOException ignored) {
  // Ignored
  }
- if (c != null) {
- bibEntry.setField(FieldName.YEAR, String.valueOf(c.get(Calendar.YEAR)));
+ if (calender != null) {
+ bibEntry.setField(FieldName.YEAR, String.valueOf(calender.get(Calendar.YEAR)));
  if (date.length() > 4) {
- Optional<Month> month = Month.getMonthByNumber(c.get(Calendar.MONTH) + 1);
+ Optional<Month> month = Month.getMonthByNumber(calender.get(Calendar.MONTH) + 1);
  month.ifPresent(bibEntry::setMonth);
  }
  }
@@ -92,9 +94,9 @@ private void extractYearAndMonth() {
  * @param dcSchema Metadata in DublinCore format.
  */
  private void extractAbstract() {
- String s = dcSchema.getDescription();
- if (s != null) {
- bibEntry.setField(FieldName.ABSTRACT, s);
+ String description = dcSchema.getDescription();
+ if (!StringUtil.isNullOrEmpty(description)) {
+ bibEntry.setField(FieldName.ABSTRACT, description);
  }
  }
 
@@ -105,9 +107,9 @@ private void extractAbstract() {
  * @param dcSchema Metadata in DublinCore format.
  */
  private void extractDOI() {
- String s = dcSchema.getIdentifier();
- if (s != null) {
- bibEntry.setField(FieldName.DOI, s);
+ String identifier = dcSchema.getIdentifier();
+ if (!StringUtils.isNullOrEmpty(identifier)) {
+ bibEntry.setField(FieldName.DOI, identifier);
  }
  }
 
@@ -154,9 +156,9 @@ private void extractBibTexFields() {
  * @param dcSchema Metadata in DublinCore format.
  */
  private void extractRights() {
- String s = dcSchema.getRights();
- if (s != null) {
- bibEntry.setField("rights", s);
+ String rights = dcSchema.getRights();
+ if (!StringUtils.isNullOrEmpty(rights)) {
+ bibEntry.setField("rights", rights);
  }
  }
 
@@ -167,9 +169,9 @@ private void extractRights() {
  * @param dcSchema Metadata in DublinCore format.
  */
  private void extractSource() {
- String s = dcSchema.getSource();
- if (s != null) {
- bibEntry.setField("source", s);
+ String source = dcSchema.getSource();
+ if (!StringUtils.isNullOrEmpty(source)) {
+ bibEntry.setField("source", source);
  }
  }
 
@@ -180,7 +182,7 @@ private void extractSource() {
  */
  private void extractSubject() {
  List<String> subjects = dcSchema.getSubjects();
- if (subjects != null) {
+ if ((subjects != null) && !subjects.isEmpty()) {
  bibEntry.addKeywords(subjects, xmpPreferences.getKeywordSeparator());
  }
  }
@@ -192,9 +194,9 @@ private void extractSubject() {
  * @param dcSchema Metadata in DublinCore format.
  */
  private void extractTitle() {
- String s = dcSchema.getTitle();
- if (s != null) {
- bibEntry.setField(FieldName.TITLE, s);
+ String title = dcSchema.getTitle();
+ if (!StringUtil.isNullOrEmpty(title)) {
+ bibEntry.setField(FieldName.TITLE, title);
  }
  }
 
@@ -205,11 +207,11 @@ private void extractTitle() {
  * @param dcSchema Metadata in DublinCore format.
  */
  private void extractType() {
- List<String> l = dcSchema.getTypes();
- if ((l != null) && !l.isEmpty()) {
- String s = l.get(0);
- if (s != null) {
- bibEntry.setType(s);
+ List<String> types = dcSchema.getTypes();
+ if ((types != null) && !types.isEmpty()) {
+ String type = types.get(0);
+ if (!StringUtils.isNullOrEmpty(type)) {
+ bibEntry.setType(type);
  }
  }
  }