Class ArrayUtilities

java.lang.Object
com.cedarsoftware.util.ArrayUtilities
public final class ArrayUtilities extends Object
Handy utilities for working with Java arrays.
Author:
Ken Partlow, John DeRegnaucourt ([email protected])
Copyright (c) Cedar Software LLC

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

License

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

  • Field Details

    • EMPTY_OBJECT_ARRAY

      public static final Object[] EMPTY_OBJECT_ARRAY
      Immutable common arrays.

    • EMPTY_BYTE_ARRAY

      public static final byte[] EMPTY_BYTE_ARRAY

    • EMPTY_CHAR_ARRAY

      public static final char[] EMPTY_CHAR_ARRAY

    • EMPTY_CHARACTER_ARRAY

      public static final Character[] EMPTY_CHARACTER_ARRAY

    • EMPTY_CLASS_ARRAY

      public static final Class[] EMPTY_CLASS_ARRAY

  • Method Details

    • isEmpty

      public static boolean isEmpty(Object array)
      This is a null-safe isEmpty check. It uses the Array static class for doing a length check. This check is actually .0001 ms slower than the following typed check:

      return array == null || array.length == 0;

      but gives you more flexibility, since it checks for all array types.
      Parameters:
      array - array to check
      Returns:
      true if empty or null

    • size

      public static int size(Object array)
      This is a null-safe size check. It uses the Array static class for doing a length check. This check is actually .0001 ms slower than the following typed check:

      return (array == null) ? 0 : array.length;

      Parameters:
      array - array to check
      Returns:
      true if empty or null

    • shallowCopy

      public static <T> T[] shallowCopy(T[] array)

      Shallow copies an array of Objects

      The objects in the array are not cloned, thus there is no special handling for multi-dimensional arrays.

      This method returns null if null array input.

      Type Parameters:
      T - the array type
      Parameters:
      array - the array to shallow clone, may be null
      Returns:
      the cloned array, null if null input

    • createArray

      @SafeVarargs public static <T> T[] createArray(T... elements)
      Creates and returns an array containing the provided elements.

      This method accepts a variable number of arguments and returns them as an array of type T[]. It is primarily used to facilitate array creation in generic contexts, where type inference is necessary.

      Example Usage: 

      
 String[] stringArray = createArray("Apple", "Banana", "Cherry");
 Integer[] integerArray = createArray(1, 2, 3, 4);
 Person[] personArray = createArray(new Person("Alice"), new Person("Bob"));

      Important Considerations:

      • Type Safety: Due to type erasure in Java generics, this method does not perform any type checks beyond what is already enforced by the compiler. Ensure that all elements are of the expected type T to avoid ClassCastException at runtime.
      • Heap Pollution: The method is annotated with SafeVarargs to suppress warnings related to heap pollution when using generics with varargs. It is safe to use because the method does not perform any unsafe operations on the varargs parameter.
      • Null Elements: The method does not explicitly handle null elements. If null values are passed, they will be included in the returned array.
      • Immutable Arrays: The returned array is mutable. To create an immutable array, consider wrapping it using Collections.unmodifiableList(List) or using third-party libraries like Guava's
        invalid reference 
        com.google.common.collect.ImmutableList
        .
      Type Parameters:
      T - the component type of the array
      Parameters:
      elements - the elements to be stored in the array
      Returns:
      an array containing the provided elements
      Throws:
      NullPointerException - if the elements array is null

    • addAll

      public static <T> T[] addAll(T[] array1, T[] array2)

      Adds all the elements of the given arrays into a new array.

      The new array contains all of the element of array1 followed by all of the elements array2. When an array is returned, it is always a new array. 

       ArrayUtilities.addAll(null, null)     = null
 ArrayUtilities.addAll(array1, null)   = cloned copy of array1
 ArrayUtilities.addAll(null, array2)   = cloned copy of array2
 ArrayUtilities.addAll([], [])         = []
 ArrayUtilities.addAll([null], [null]) = [null, null]
 ArrayUtilities.addAll(["a", "b", "c"], ["1", "2", "3"]) = ["a", "b", "c", "1", "2", "3"]
      Type Parameters:
      T - the array type
      Parameters:
      array1 - the first array whose elements are added to the new array, may be null
      array2 - the second array whose elements are added to the new array, may be null
      Returns:
      The new array, null if null array inputs. The type of the new array is the type of the first array.

    • removeItem

      public static <T> T[] removeItem(T[] array, int pos)

    • getArraySubset

      public static <T> T[] getArraySubset(T[] array, int start, int end)

    • toArray

      public static <T> T[] toArray(Class<T> classToCastTo, Collection<?> c)
      Convert Collection to a Java (typed) array [].
      Type Parameters:
      T - Type of the array
      Parameters:
      classToCastTo - array type (Object[], Person[], etc.)
      c - Collection containing items to be placed into the array.
      Returns:
      Array of the type (T) containing the items from collection 'c'.