Class Data


  • public class Data
    extends Object
    Utilities for working with key/value data based on the Key annotation.
    Since:
    1.4
    Author:
    Yaniv Inbar
    • Field Detail

      • NULL_BOOLEAN

        public static final Boolean NULL_BOOLEAN
        The single instance of the magic null object for a Boolean.
      • NULL_STRING

        public static final String NULL_STRING
        The single instance of the magic null object for a String.
      • NULL_CHARACTER

        public static final Character NULL_CHARACTER
        The single instance of the magic null object for a Character.
      • NULL_BYTE

        public static final Byte NULL_BYTE
        The single instance of the magic null object for a Byte.
      • NULL_SHORT

        public static final Short NULL_SHORT
        The single instance of the magic null object for a Short.
      • NULL_INTEGER

        public static final Integer NULL_INTEGER
        The single instance of the magic null object for a Integer.
      • NULL_FLOAT

        public static final Float NULL_FLOAT
        The single instance of the magic null object for a Float.
      • NULL_LONG

        public static final Long NULL_LONG
        The single instance of the magic null object for a Long.
      • NULL_DOUBLE

        public static final Double NULL_DOUBLE
        The single instance of the magic null object for a Double.
      • NULL_BIG_INTEGER

        public static final BigInteger NULL_BIG_INTEGER
        The single instance of the magic null object for a BigInteger.
      • NULL_BIG_DECIMAL

        public static final BigDecimal NULL_BIG_DECIMAL
        The single instance of the magic null object for a BigDecimal.
      • NULL_DATE_TIME

        public static final DateTime NULL_DATE_TIME
        The single instance of the magic null object for a DateTime.
    • Constructor Detail

      • Data

        public Data()
    • Method Detail

      • nullOf

        public static <T> T nullOf​(Class<?> objClass)
        Returns the single instance of the magic object that represents the "null" value for the given Java class (including array or enum).
        Parameters:
        objClass - class of the object needed
        Returns:
        magic object instance that represents the "null" value (not Java null)
        Throws:
        IllegalArgumentException - if unable to create a new instance
      • isNull

        public static boolean isNull​(Object object)
        Returns whether the given object is the magic object that represents the null value of its class.
        Parameters:
        object - object or null
        Returns:
        whether it is the magic null value or false for null input
      • mapOf

        public static Map<String,​Object> mapOf​(Object data)
        Returns the map to use for the given data that is treated as a map from string key to some value.

        If the input is null, it returns an empty map. If the input is a map, it simply returns the input. Otherwise, it will create a map view using reflection that is backed by the object, so that any changes to the map will be reflected on the object. The map keys of that map view are based on the Key annotation, and null is not a possible map value, although the magic null instance is possible (see nullOf(Class) and isNull(Object)). Iteration order of the data keys is based on the sorted (ascending) key names of the declared fields. Note that since the map view is backed by the object, and that the object may change, many methods in the map view must recompute the field values using reflection, for example Map.size() must check the number of non-null fields.

        Parameters:
        data - any key value data, represented by an object or a map, or null
        Returns:
        key/value map to use
      • clone

        public static <T> T clone​(T data)
        Returns a deep clone of the given key/value data, such that the result is a completely independent copy.

        This should not be used directly in the implementation of Object.clone(). Instead use deepCopy(Object, Object) for that purpose.

        Final fields cannot be changed and therefore their value won't be copied.

        Parameters:
        data - key/value data object or map to clone or null for a null return value
        Returns:
        deep clone or null for null input
      • deepCopy

        public static void deepCopy​(Object src,
                                    Object dest)
        Makes a deep copy of the given source object into the destination object that is assumed to be constructed using Object.clone().

        Example usage of this method in Object.clone():

          @Override
          public MyObject clone() {
            try {
              @SuppressWarnings("unchecked")
              MyObject result = (MyObject) super.clone();
              Data.deepCopy(this, result);
              return result;
            } catch (CloneNotSupportedException e) {
              throw new IllegalStateException(e);
            }
          }
         

        Final fields cannot be changed and therefore their value won't be copied.

        Parameters:
        src - source object
        dest - destination object of identical type as source object, and any contained arrays must be the same length
      • isValueOfPrimitiveType

        public static boolean isValueOfPrimitiveType​(Object fieldValue)
        Returns whether to given value is null or its class is primitive as defined by isPrimitive(Type).
      • resolveWildcardTypeOrTypeVariable

        public static Type resolveWildcardTypeOrTypeVariable​(List<Type> context,
                                                             Type type)
        Aggressively resolves the given type in such a way that the resolved type is not a wildcard type or a type variable, returning Object.class if the type variable cannot be resolved.
        Parameters:
        context - context list, ordering from least specific to most specific type context, for example container class and then its field
        type - type or null for null result
        Returns:
        resolved type (which may be class, parameterized type, or generic array type, but not wildcard type or type variable) or null for null input