fix(code): Small code clean up

src/main/java/com/cronutils/descriptor/CronDescriptor.java

@@ -143,7 +143,7 @@ public String describeDayOfWeek(final Map<CronFieldName, CronField> fields, fina
         final String description = DescriptionStrategyFactory.daysOfWeekInstance(
                 resourceBundle,
                 fields.containsKey(CronFieldName.DAY_OF_WEEK) ? fields.get(CronFieldName.DAY_OF_WEEK).getExpression() : null,
-                definitions.containsKey(CronFieldName.DAY_OF_WEEK) ? definitions.get(CronFieldName.DAY_OF_WEEK) : null
+                definitions.getOrDefault(CronFieldName.DAY_OF_WEEK, null)
         ).describe();
         return addExpressions(description, resourceBundle.getString("day"), resourceBundle.getString("days"));
     }

src/main/java/com/cronutils/descriptor/TimeDescriptionStrategy.java

@@ -303,7 +303,7 @@ private void registerFunctions() {
 	/**
 	 * Contains CronFieldExpression instances for hours, minutes and seconds.
 	 */
-	class TimeFields {
+	static class TimeFields {
 		private final FieldExpression seconds;
 		private final FieldExpression minutes;
 		private final FieldExpression hours;

src/main/java/com/cronutils/model/definition/CronDefinitionBuilder.java

@@ -240,8 +240,7 @@ public void register(final FieldDefinition definition) {
      * @return returns CronDefinition instance, never null
      */
     public CronDefinition instance() {
-        final Set<CronConstraint> validations = new HashSet<>();
-        validations.addAll(cronConstraints);
+        final Set<CronConstraint> validations = new HashSet<>(cronConstraints);
         final List<FieldDefinition> values = new ArrayList<>(fields.values());
         values.sort(FieldDefinition.createFieldDefinitionComparator());
         return new CronDefinition(values, validations, cronNicknames, matchDayOfWeekAndDayOfMonth);

src/main/java/com/cronutils/model/definition/CronNicknames.java

@@ -1,5 +1,5 @@
 package com.cronutils.model.definition;
 
 public enum CronNicknames {
-    YEARLY, ANNUALLY, MONTHLY, WEEKLY, DAILY, MIDNIGHT, HOURLY, REBOOT;
+    YEARLY, ANNUALLY, MONTHLY, WEEKLY, DAILY, MIDNIGHT, HOURLY, REBOOT
 }

src/main/java/com/cronutils/model/field/CronFieldName.java

@@ -23,7 +23,7 @@ public enum CronFieldName {
      * effective bi-, tri- or quad-weekly schedules via proprietary cron expressions.
      */
 
-    private int order;
+    private final int order;
 
     /**
      * Constructor.

src/main/java/com/cronutils/model/field/expression/And.java

@@ -50,7 +50,7 @@ public String asString() {
             builder.append(expressions.get(j).asString());
             builder.append(",");
         }
-        if(expressions.size()>0){
+        if(!expressions.isEmpty()){
             builder.append(expressions.get(expressions.size() - 1).asString());
         }
         return builder.toString();

src/main/java/com/cronutils/model/field/expression/Weekdays.java

@@ -22,7 +22,7 @@
 public enum Weekdays {
     MONDAY(1), TUESDAY(2), WEDNESDAY(3), THURSDAY(4), FRIDAY(5), SATURDAY(6), SUNDAY(7);
 
-    private int weekday;
+    private final int weekday;
 
     Weekdays(int weekday) {
         this.weekday = weekday;

src/main/java/com/cronutils/model/field/value/SpecialCharFieldValue.java

@@ -18,7 +18,7 @@
 public class SpecialCharFieldValue extends FieldValue<SpecialChar> {
 
     private static final long serialVersionUID = -2177180413324528746L;
-    private SpecialChar specialChar = SpecialChar.NONE;
+    private SpecialChar specialChar;
 
     public SpecialCharFieldValue(final SpecialChar specialChar) {
         Preconditions.checkNotNull(specialChar, "special char must not be null");

src/main/java/com/cronutils/model/time/CompositeExecutionTime.java

@@ -58,6 +58,6 @@ public Optional<Duration> timeFromLastExecution(ZonedDateTime date) {
 
     @Override
     public boolean isMatch(ZonedDateTime date) {
-        return executionTimes.parallelStream().map(e->e.isMatch(date)).filter(v-> v).count()>0;
+        return executionTimes.parallelStream().map(e -> e.isMatch(date)).anyMatch(v -> v);
     }
 }

src/main/java/com/cronutils/model/time/ExecutionTime.java

@@ -35,7 +35,7 @@ public interface ExecutionTime {
      * @param cron - Cron instance
      * @return ExecutionTime instance
      */
-    public static ExecutionTime forCron(final Cron cron) {
+    static ExecutionTime forCron(final Cron cron) {
         if (cron instanceof SingleCron) {
             final Map<CronFieldName, CronField> fields = cron.retrieveFieldsAsMap();
             final ExecutionTimeBuilder executionTimeBuilder = new ExecutionTimeBuilder(cron);

src/test/java/com/cronutils/Issue305Test.java

@@ -33,7 +33,7 @@ public void testIssue305(){
             dates.add(nextExecution.get());
             nextExecution = executionTime.nextExecution(nextExecution.get());
         }
-        Set<Integer> years = dates.stream().map(d->d.getYear()).collect(Collectors.toSet());
+        Set<Integer> years = dates.stream().map(ZonedDateTime::getYear).collect(Collectors.toSet());
         Set<Integer> expectedYears = new HashSet<>();
         expectedYears.add(2015);
         expectedYears.add(2017);

src/test/java/com/cronutils/Issue423Test.java

@@ -43,7 +43,7 @@ public void issue423() {
         final CronParser parser = new CronParser(CronDefinitionBuilder.instanceDefinitionFor(CronType.QUARTZ));
         final Cron cron = parser.parse("0 0 0-07,17-0 ? * SAT");
         final CronDescriptor cd = CronDescriptor.instance(Locale.UK);
-        assertTrue(cd.describe(cron).length() > 0);
+        assertTrue(!cd.describe(cron).isEmpty());
         // at time of test creation, the descriptor is
         // "every hour between 0 and 7 and every hour between 17 and 0 at Saturday day"
 

src/test/java/com/cronutils/converter/CronConverterTest.java

@@ -31,7 +31,7 @@ public class CronConverterTest {
 
     // Fix the date to prevent test failure during the transition between Standard Time and Daylight Time.
     Function<ZoneId, Calendar> calendarFactory = (zoneId) -> {
-        Calendar fixedDay = new GregorianCalendar(2020, 06, 01);
+        Calendar fixedDay = new GregorianCalendar(2020, Calendar.JULY, 01);
         fixedDay.setTimeZone(TimeZone.getTimeZone(zoneId));
         return fixedDay;
     };

src/test/java/com/cronutils/model/field/expression/FieldExpressionTest.java

@@ -36,7 +36,7 @@ public void testAnd() {
         assertTrue(and.getExpressions().contains(testCronFieldExpression));
     }
 
-    class TestFieldExpression extends FieldExpression {
+    static class TestFieldExpression extends FieldExpression {
 
         private static final long serialVersionUID = 8101930390397976027L;
 

src/test/java/com/cronutils/parser/CronParserTest.java

@@ -71,7 +71,7 @@ public void testParseIncompleteEvery() {
     private static void validateExpression(CronType cronType, String expression) {
         CronDefinition cronDefinition = CronDefinitionBuilder.instanceDefinitionFor(cronType);
         CronParser parser = new CronParser(cronDefinition);
-        System.out.println(String.format("Validating expression '%s' using %s definition", expression, cronType));
+        System.out.printf("Validating expression '%s' using %s definition%n", expression, cronType);
         parser.parse(expression);
     }