Package org.kiwiproject.beta.collect

Class KiwiArrays2

  • @Beta
public final class KiwiArrays2
extends Object
    Utilities related to arrays.

    These utilities can be considered for inclusion into kiwi's KiwiArrays class.

    • Method Detail

      • emptyArray

        public static <T> T[] emptyArray​(Class<T> type)
        Creates an empty array of the specified type.
        Type Parameters:
        T - the type parameter representing the component type of the array
        Parameters:
        type - the class object representing the component type of the array
        Returns:
        an empty array of the specified type
        Throws:
        IllegalArgumentException - if type is null or is Void.TYPE
        See Also:
        Array.newInstance(Class, int)
        Implementation Note:
        This method exists because Array.newInstance(Class, int) returns Object and thus requires a cast. Using this method, code can be a little cleaner without a cast.

      • newArray

        public static <T> T[] newArray​(Class<T> type,
                               int length)
        Creates a new array of the specified type and length. All values in the array are null.
        Type Parameters:
        T - the type parameter representing the component type of the array
        Parameters:
        type - the class object representing the component type of the array
        length - the length of the new array
        Returns:
        a new array of the specified type and length
        Throws:
        IllegalArgumentException - if type is null or is Void.TYPE, or length is negative
        See Also:
        Array.newInstance(Class, int)
        Implementation Note:
        This method exists because Array.newInstance(Class, int) returns Object and thus requires a cast. Using this method, code can be a little cleaner without a cast.

      • primitiveToObjectArrayOrNull

        public static <T> @Nullable T[] primitiveToObjectArrayOrNull​(@Nullable Object primitiveArray,
                                                             Class<T> wrapperType)
        Convert an array of primitives to an array of the corresponding wrapper type.
        Type Parameters:
        T - the wrapper type corresponding to the input array's primitive type
        Parameters:
        primitiveArray - an array of primitives
        wrapperType - the wrapper type of the primitive type
        Returns:
        an array of the wrapper type, or null if the input array is null
        Throws:
        IllegalArgumentException - if the input array is not an array of primitives, or the wrapper type is not a primitive wrapper class
        Implementation Note:
        Intentionally suppressing Sonar java:S1168 (Return an empty array instead of null) because the method is explicit that it returns null when given null input.

      • primitiveToObjectArrayOrEmpty

        public static <T> Optional<T[]> primitiveToObjectArrayOrEmpty​(@Nullable Object primitiveArray,
                                                              Class<T> wrapperType)
        Convert an array of primitives to an array of the corresponding wrapper type.
        Type Parameters:
        T - the wrapper type corresponding to the input array's primitive type
        Parameters:
        primitiveArray - an array of primitives
        wrapperType - the wrapper type of the primitive type
        Returns:
        an Optional containing an array of the wrapper type, or an empty Optional if the input array is null
        Throws:
        IllegalArgumentException - if the input array is not an array of primitives or the wrapper type is not a primitive wrapper class

      • primitiveToObjectArray

        public static <T> T[] primitiveToObjectArray​(Object primitiveArray,
                                             Class<T> wrapperType)
        Convert an array of primitives to an array of the corresponding wrapper type.
        Type Parameters:
        T - the wrapper type corresponding to the input array's primitive type
        Parameters:
        primitiveArray - an array of primitives
        wrapperType - the wrapper type of the primitive type
        Returns:
        an array of the wrapper type
        Throws:
        IllegalArgumentException - if the input array is null or is not an array of primitives or the wrapper type is not a primitive wrapper class
        Implementation Note:
        The internal logic is not pretty, but I cannot find an existing utility that does this (e.g. in Apache Commons or Google Guava). Apache Commons Lang's ArrayUtils is used internally to convert primitive arrays, but because of needing to handle all Java primitive types, I can't think of a cleaner way to do this other than a conditional covering all eight primitive types.