Constants and instantiation problems fix

src/main/java/graphql/scalars/ExtendedScalars.java

@@ -40,7 +40,7 @@ public class ExtendedScalars {
      * @see java.time.OffsetDateTime
      * @see java.time.ZonedDateTime
      */
-    public static GraphQLScalarType DateTime = DateTimeScalar.INSTANCE;
+    public static final GraphQLScalarType DateTime = DateTimeScalar.INSTANCE;
 
     /**
      * An RFC-3339 compliant date scalar that accepts string values like `1996-12-19` and produces
@@ -53,7 +53,7 @@ public class ExtendedScalars {
      *
      * @see java.time.LocalDate
      */
-    public static GraphQLScalarType Date = DateScalar.INSTANCE;
+    public static final GraphQLScalarType Date = DateScalar.INSTANCE;
     /**
      * An RFC-3339 compliant time scalar that accepts string values like `6:39:57-08:00` and produces
      * `java.time.OffsetTime` objects at runtime.
@@ -65,7 +65,7 @@ public class ExtendedScalars {
      *
      * @see java.time.OffsetTime
      */
-    public static GraphQLScalarType Time = TimeScalar.INSTANCE;
+    public static final GraphQLScalarType Time = TimeScalar.INSTANCE;
 
     /**
      * A 24-hour local time scalar that accepts strings like `hh:mm:ss` and `hh:mm:ss.sss` and produces
@@ -76,7 +76,7 @@ public class ExtendedScalars {
      *
      * @see java.time.LocalTime
      */
-    public static GraphQLScalarType LocalTime = GraphQLScalarType.newScalar()
+    public static final GraphQLScalarType LocalTime = GraphQLScalarType.newScalar()
             .name("LocalTime")
             .description("24-hour clock time value string in the format `hh:mm:ss` or `hh:mm:ss.sss`.")
             .coercing(new LocalTimeCoercing())
@@ -105,7 +105,7 @@ public class ExtendedScalars {
      *
      * @see #Json
      */
-    public static GraphQLScalarType Object = ObjectScalar.INSTANCE;
+    public static final GraphQLScalarType Object = ObjectScalar.INSTANCE;
 
     /**
      * A synonym class for the {@link #Object} scalar, since some people prefer their SDL to look like the following :
@@ -122,68 +122,68 @@ public class ExtendedScalars {
      *
      * @see graphql.scalars.ExtendedScalars#Object
      */
-    public static GraphQLScalarType Json = JsonScalar.INSTANCE;
+    public static final GraphQLScalarType Json = JsonScalar.INSTANCE;
 
     /**
      * A URL scalar that accepts URL strings and produces {@link java.net.URL} objects at runtime
      */
-    public static GraphQLScalarType Url = UrlScalar.INSTANCE;
+    public static final GraphQLScalarType Url = UrlScalar.INSTANCE;
 
     /**
      * A Locale scalar that accepts a IETF BCP 47 language tag string and produces {@link
      * java.util.Locale} objects at runtime.
      */
-    public static GraphQLScalarType Locale = LocaleScalar.INSTANCE;
+    public static final GraphQLScalarType Locale = LocaleScalar.INSTANCE;
 
     /**
      * An `Int` scalar that MUST be greater than zero
      *
      * @see graphql.Scalars#GraphQLInt
      */
-    public static GraphQLScalarType PositiveInt = PositiveIntScalar.INSTANCE;
+    public static final GraphQLScalarType PositiveInt = PositiveIntScalar.INSTANCE;
     /**
      * An `Int` scalar that MUST be less than zero
      *
      * @see graphql.Scalars#GraphQLInt
      */
-    public static GraphQLScalarType NegativeInt = NegativeIntScalar.INSTANCE;
+    public static final GraphQLScalarType NegativeInt = NegativeIntScalar.INSTANCE;
     /**
      * An `Int` scalar that MUST be less than or equal to zero
      *
      * @see graphql.Scalars#GraphQLInt
      */
-    public static GraphQLScalarType NonPositiveInt = NonPositiveIntScalar.INSTANCE;
+    public static final GraphQLScalarType NonPositiveInt = NonPositiveIntScalar.INSTANCE;
     /**
      * An `Int` scalar that MUST be greater than or equal to zero
      *
      * @see graphql.Scalars#GraphQLInt
      */
-    public static GraphQLScalarType NonNegativeInt = NonNegativeIntScalar.INSTANCE;
+    public static final GraphQLScalarType NonNegativeInt = NonNegativeIntScalar.INSTANCE;
 
     /**
      * An `Float` scalar that MUST be greater than zero
      *
      * @see graphql.Scalars#GraphQLFloat
      */
-    public static GraphQLScalarType PositiveFloat = PositiveFloatScalar.INSTANCE;
+    public static final GraphQLScalarType PositiveFloat = PositiveFloatScalar.INSTANCE;
     /**
      * An `Float` scalar that MUST be less than zero
      *
      * @see graphql.Scalars#GraphQLFloat
      */
-    public static GraphQLScalarType NegativeFloat = NegativeFloatScalar.INSTANCE;
+    public static final GraphQLScalarType NegativeFloat = NegativeFloatScalar.INSTANCE;
     /**
      * An `Float` scalar that MUST be less than or equal to zero
      *
      * @see graphql.Scalars#GraphQLFloat
      */
-    public static GraphQLScalarType NonPositiveFloat = NonPositiveFloatScalar.INSTANCE;
+    public static final GraphQLScalarType NonPositiveFloat = NonPositiveFloatScalar.INSTANCE;
     /**
      * An `Float` scalar that MUST be greater than or equal to zero
      *
      * @see graphql.Scalars#GraphQLFloat
      */
-    public static GraphQLScalarType NonNegativeFloat = NonNegativeFloatScalar.INSTANCE;
+    public static final GraphQLScalarType NonNegativeFloat = NonNegativeFloatScalar.INSTANCE;
 
 
     /**

src/main/java/graphql/scalars/alias/AliasedScalar.java

@@ -15,7 +15,9 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#newAliasedScalar(String)}
  */
 @Internal
-public class AliasedScalar {
+public final class AliasedScalar {
+
+    private AliasedScalar() {}
 
     /**
      * A builder for {@link graphql.scalars.alias.AliasedScalar}

src/main/java/graphql/scalars/datetime/DateScalar.java

@@ -22,11 +22,13 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#Date}
  */
 @Internal
-public class DateScalar  {
+public final class DateScalar  {
 
-    private final static DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+    private static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
 
-    public static GraphQLScalarType INSTANCE;
+    public static final GraphQLScalarType INSTANCE;
+
+    private DateScalar() {}
 
     static {
         Coercing<LocalDate, String> coercing = new Coercing<LocalDate, String>() {
@@ -43,7 +45,7 @@ public String serialize(Object input) throws CoercingSerializeException {
                     );
                 }
                 try {
-                    return dateFormatter.format(temporalAccessor);
+                    return DATE_FORMATTER.format(temporalAccessor);
                 } catch (DateTimeException e) {
                     throw new CoercingSerializeException(
                             "Unable to turn TemporalAccessor into full date because of : '" + e.getMessage() + "'."
@@ -90,7 +92,7 @@ public Value<?> valueToLiteral(Object input) {
 
             private LocalDate parseLocalDate(String s, Function<String, RuntimeException> exceptionMaker) {
                 try {
-                    TemporalAccessor temporalAccessor = dateFormatter.parse(s);
+                    TemporalAccessor temporalAccessor = DATE_FORMATTER.parse(s);
                     return LocalDate.from(temporalAccessor);
                 } catch (DateTimeParseException e) {
                     throw exceptionMaker.apply("Invalid RFC3339 full date value : '" + s + "'. because of : '" + e.getMessage() + "'");

src/main/java/graphql/scalars/datetime/DateTimeScalar.java

@@ -22,9 +22,11 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#DateTime}
  */
 @Internal
-public class DateTimeScalar {
+public final class DateTimeScalar {
 
-    public static GraphQLScalarType INSTANCE;
+    public static final GraphQLScalarType INSTANCE;
+
+    private DateTimeScalar() {}
 
     static {
         Coercing<OffsetDateTime, String> coercing = new Coercing<OffsetDateTime, String>() {

src/main/java/graphql/scalars/datetime/LocalTimeCoercing.java

@@ -17,7 +17,7 @@
 
 public class LocalTimeCoercing implements Coercing<LocalTime, String> {
 
-    private final static DateTimeFormatter dateFormatter = DateTimeFormatter.ISO_LOCAL_TIME;
+    private static final DateTimeFormatter DATE_FORMATTER = DateTimeFormatter.ISO_LOCAL_TIME;
 
     @Override
     public String serialize(final Object input) throws CoercingSerializeException {
@@ -32,7 +32,7 @@ public String serialize(final Object input) throws CoercingSerializeException {
             );
         }
         try {
-            return dateFormatter.format(temporalAccessor);
+            return DATE_FORMATTER.format(temporalAccessor);
         } catch (DateTimeException e) {
             throw new CoercingSerializeException(
                     "Unable to turn TemporalAccessor into full time because of : '" + e.getMessage() + "'."
@@ -73,7 +73,7 @@ public LocalTime parseLiteral(final Object input) throws CoercingParseLiteralExc
 
     private static LocalTime parseTime(String s, Function<String, RuntimeException> exceptionMaker) {
         try {
-            TemporalAccessor temporalAccessor = dateFormatter.parse(s);
+            TemporalAccessor temporalAccessor = DATE_FORMATTER.parse(s);
             return LocalTime.from(temporalAccessor);
         } catch (DateTimeParseException e) {
             throw exceptionMaker.apply("Invalid local time value : '" + s + "'. because of : '" + e.getMessage() + "'");

src/main/java/graphql/scalars/datetime/TimeScalar.java

@@ -22,11 +22,13 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#Time}
  */
 @Internal
-public class TimeScalar {
+public final class TimeScalar {
 
-    private final static DateTimeFormatter dateFormatter = DateTimeFormatter.ISO_OFFSET_TIME;
+    private static final DateTimeFormatter dateFormatter = DateTimeFormatter.ISO_OFFSET_TIME;
 
-    public static GraphQLScalarType INSTANCE;
+    public static final GraphQLScalarType INSTANCE;
+
+    private TimeScalar() {}
 
     static {
         Coercing<OffsetTime, String> coercing = new Coercing<OffsetTime, String>() {

src/main/java/graphql/scalars/java/JavaPrimitives.java

@@ -19,7 +19,9 @@
  * Access these via {@link graphql.scalars.ExtendedScalars}
  */
 @Internal
-public class JavaPrimitives {
+public final class JavaPrimitives {
+
+    private JavaPrimitives() {}
 
     private static final BigInteger LONG_MAX = BigInteger.valueOf(Long.MAX_VALUE);
     private static final BigInteger LONG_MIN = BigInteger.valueOf(Long.MIN_VALUE);

src/main/java/graphql/scalars/locale/LocaleScalar.java

@@ -17,9 +17,11 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#Locale}
  */
 @Internal
-public class LocaleScalar {
+public final class LocaleScalar {
 
-    public static GraphQLScalarType INSTANCE;
+    private LocaleScalar() {}
+
+    public static final GraphQLScalarType INSTANCE;
 
     static {
         Coercing<Locale, String> coercing = new Coercing<Locale, String>() {

src/main/java/graphql/scalars/numeric/FloatCoercing.java

@@ -14,7 +14,7 @@
 @Internal
 abstract class FloatCoercing implements Coercing<Double, Double> {
 
-    abstract protected Double check(Double d, Function<String, RuntimeException> exceptionMaker);
+    protected abstract Double check(Double d, Function<String, RuntimeException> exceptionMaker);
 
     @Override
     public Double serialize(Object input) throws CoercingSerializeException {

src/main/java/graphql/scalars/numeric/IntCoercing.java

@@ -14,7 +14,7 @@
 @Internal
 abstract class IntCoercing implements Coercing<Integer, Integer> {
 
-    abstract protected Integer check(Integer i, Function<String, RuntimeException> exceptionMaker);
+    protected abstract Integer check(Integer i, Function<String, RuntimeException> exceptionMaker);
 
     @Override
     public Integer serialize(Object input) throws CoercingSerializeException {

src/main/java/graphql/scalars/numeric/NegativeFloatScalar.java

@@ -9,15 +9,17 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#NegativeFloat}
  */
 @Internal
-public class NegativeFloatScalar {
+public final class NegativeFloatScalar {
 
-    public static GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
+    private NegativeFloatScalar() {}
+
+    public static final GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
             .name("NegativeFloat")
             .description("An Float scalar that must be a negative value")
             .coercing(new FloatCoercing() {
                 @Override
                 protected Double check(Double d, Function<String, RuntimeException> exceptionMaker) {
-                    if (!(d < 0)) {
+                    if (d >= 0.0d) {
                         throw exceptionMaker.apply("The value must be a negative value");
                     }
                     return d;

src/main/java/graphql/scalars/numeric/NegativeIntScalar.java

@@ -9,15 +9,17 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#NegativeInt}
  */
 @Internal
-public class NegativeIntScalar {
+public final class NegativeIntScalar {
 
-    public static GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
+    private NegativeIntScalar() {}
+
+    public static final GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
             .name("NegativeInt")
             .description("An Int scalar that must be a negative value")
             .coercing(new IntCoercing() {
                 @Override
                 protected Integer check(Integer i, Function<String, RuntimeException> exceptionMaker) {
-                    if (!(i < 0)) {
+                    if (i >= 0) {
                         throw exceptionMaker.apply("The value must be a negative integer");
                     }
                     return i;

src/main/java/graphql/scalars/numeric/NonNegativeFloatScalar.java

@@ -9,15 +9,17 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#NonNegativeFloat}
  */
 @Internal
-public class NonNegativeFloatScalar {
+public final class NonNegativeFloatScalar {
 
-    public static GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
+    private NonNegativeFloatScalar() {}
+
+    public static final GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
             .name("NonNegativeFloat")
             .description("An Float scalar that must be greater than or equal to zero")
             .coercing(new FloatCoercing() {
                 @Override
                 protected Double check(Double d, Function<String, RuntimeException> exceptionMaker) {
-                    if (!(d >= 0)) {
+                    if (d < 0.0d) {
                         throw exceptionMaker.apply("The value must be greater than or equal to zero");
                     }
                     return d;

src/main/java/graphql/scalars/numeric/NonNegativeIntScalar.java

@@ -9,15 +9,17 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#NonNegativeInt}
  */
 @Internal
-public class NonNegativeIntScalar {
+public final class NonNegativeIntScalar {
 
-    public static GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
+    private NonNegativeIntScalar() {}
+
+    public static final GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
             .name("NonNegativeInt")
             .description("An Int scalar that must be greater than or equal to zero")
             .coercing(new IntCoercing() {
                 @Override
                 protected Integer check(Integer i, Function<String, RuntimeException> exceptionMaker) {
-                    if (!(i >= 0)) {
+                    if (i < 0) {
                         throw exceptionMaker.apply("The value must be greater than or equal to zero");
                     }
                     return i;

src/main/java/graphql/scalars/numeric/NonPositiveFloatScalar.java

@@ -9,13 +9,16 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#NonPositiveFloat}
  */
 @Internal
-public class NonPositiveFloatScalar {
-    public static GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
+public final class NonPositiveFloatScalar {
+
+    private NonPositiveFloatScalar() {}
+
+    public static final GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
             .name("NonPositiveFloat").description("An Float scalar that must be less than or equal to zero")
             .coercing(new FloatCoercing() {
                 @Override
                 protected Double check(Double d, Function<String, RuntimeException> exceptionMaker) {
-                    if (!(d <= 0)) {
+                    if (d > 0) {
                         throw exceptionMaker.apply("The value must be less than or equal to zero");
                     }
                     return d;

src/main/java/graphql/scalars/numeric/NonPositiveIntScalar.java

@@ -9,14 +9,17 @@
  * Access this via {@link graphql.scalars.ExtendedScalars#NonPositiveInt}
  */
 @Internal
-public class NonPositiveIntScalar {
-    public static GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
+public final class NonPositiveIntScalar {
+
+    private NonPositiveIntScalar() {}
+
+    public static final GraphQLScalarType INSTANCE = GraphQLScalarType.newScalar()
             .name("NonPositiveInt")
             .description("An Int scalar that must be less than or equal to zero")
             .coercing(new IntCoercing() {
                 @Override
                 protected Integer check(Integer i, Function<String, RuntimeException> exceptionMaker) {
-                    if (!(i <= 0)) {
+                    if (i > 0) {
                         throw exceptionMaker.apply("The value must be less than or equal to zero");
                     }
                     return i;