org.key_project.util.java

Class ArrayUtil

java.lang.Object

org.key_project.util.java.ArrayUtil

public final class ArrayUtil
extends java.lang.Object

Provides static methods to work with arrays.

Author:

Martin Hentschel

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ArrayUtil() Forbid instances by this private constructor.

Method Summary

Modifier and Type	Method and Description
static int[]	add(int[] array, int toAdd) Adds the given element to the existing array.
static <T> T[]	add(T[] array, T toAdd) Adds the given element to the existing array.
static <T> T[]	addAll(T[] array, T[] toAdd) Adds the given elements to the existing array.
static <T> T[]	addAll(T[] array, T[] toAdd, java.lang.Class<?> newArrayType) Adds the given elements to the existing array.
static <T> boolean	contains(T[] array, T toSearch) Checks if the given array contains the element to search.
static <T> boolean	contains(T[] array, T toSearch, java.util.Comparator<T> comparator) Checks if the given array contains the element to search.
static <T> T[][]	generatePermutations(T[] array) Computes all permutations of the given array using the 'Heap's algorithm'.
private static <T> int	generatePermutations(T[] array, int n, T[][] permutations, int permutationsIndex) Recursive implementation of the 'Heap's algorithm': procedure generate(n : integer, A : array of any): if n = 1 then output(A) else for i := 0; i < n; i += 1 do generate(n - 1, A) if n is even then swap(A[i], A[n-1]) else swap(A[0], A[n-1]) end if end for end if
static <T> T	getFirst(T[] array) Returns the first element from the given array.
static <T> T	getFollowing(T[] array, T toSearch) Returns the following element if available from the array.
static <T> T	getFollowing(T[] array, T toSearch, java.util.Comparator<T> comparator) Returns the following element if available from the array.
static <T> T	getLast(T[] array) Returns the last element from the given array.
static <T> T	getPrevious(T[] array, T toSearch) Returns the previous element if available from the array.
static <T> T	getPrevious(T[] array, T toSearch, java.util.Comparator<T> comparator) Returns the previous element if available from the array.
static <T> int	indexOf(T[] array, T toSearch) Returns the first index in the given array that contains the element to search.
static <T> int	indexOf(T[] array, T toSearch, java.util.Comparator<T> comparator) Returns the first index in the given array that contains the element to search.
static <T> T[]	insert(T[] array, T toInsert, int index) Inserts the given element at the given index to the existing array.
static <T> boolean	isEmpty(T[] array) Checks if the given array is empty.
static <T> boolean	isFirst(T[] array, T toSearch) Checks if the given element is the first element in the array.
static <T> boolean	isFirst(T[] array, T toSearch, java.util.Comparator<T> comparator) Checks if the given element is the first element in the array.
static <T> boolean	isLast(T[] array, T toSearch) Checks if the given element is the last element in the array.
static <T> boolean	isLast(T[] array, T toSearch, java.util.Comparator<T> comparator) Checks if the given element is the last element in the array.
static <T> T[]	remove(T[] array, T toRemove) Removes all occurrences from toRemove in the array.
static <T> T[]	remove(T[] array, T toRemove, java.util.Comparator<T> comparator) Removes all occurrences from toRemove in the array.
static <T> T	search(T[] array, IFilter<T> filter) Searches an element in the given Iterable instance.
static java.lang.String	toString(int[] array) Converts the given array into a String.
static java.lang.String	toString(int[] array, java.lang.String separator) Converts the given array into a String.
static <T> java.lang.String	toString(T... array) Converts the given array into a String.
static <T> java.lang.String	toString(T[] array, java.lang.String separator) Converts the given array into a String.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ArrayUtil

private ArrayUtil()

Forbid instances by this private constructor.

Method Detail

search

public static <T> T search(T[] array,
                           IFilter<T> filter)

Searches an element in the given Iterable instance.

Parameters:

array - The instance to search in.

filter - The filter to select an element.

Returns:

The found element or null if no element was found.

addAll

public static <T> T[] addAll(T[] array,
                             T[] toAdd)

Adds the given elements to the existing array. The result is a new array that contains the other elements in the end.

Attention: It is not possible to use this method with two null parameters. In this case is an IllegalArgumentException thrown.

Parameters:

array - The array to add to.

toAdd - The elements to add.

Returns:

The new created array.

Throws:

java.lang.IllegalArgumentException - Both parameters are null.

addAll

public static <T> T[] addAll(T[] array,
                             T[] toAdd,
                             java.lang.Class<?> newArrayType)

Adds the given elements to the existing array. The result is a new array that contains the other elements in the end.

Attention: It is not possible to use this method with two null parameters. In this case is an IllegalArgumentException thrown.

Parameters:

array - The array to add to.

toAdd - The elements to add.

newArrayType - The type of the new array.

Returns:

The new created array.

Throws:

java.lang.IllegalArgumentException - Both parameters are null.

add

public static <T> T[] add(T[] array,
                          T toAdd)

Adds the given element to the existing array. The result is a new array that contains one more element.

Attention: It is not possible to use this method with two null parameters. In this case is an IllegalArgumentException thrown.

Parameters:

array - The array to extend.

toAdd - The element to add.

Returns:

The new created array with one more element.

Throws:

java.lang.IllegalArgumentException - Both parameters are null.

add

public static int[] add(int[] array,
                        int toAdd)

Adds the given element to the existing array. The result is a new array that contains one more element.

Parameters:

array - The array to extend.

toAdd - The element to add.

Returns:

The new created array with one more element.

insert

public static <T> T[] insert(T[] array,
                             T toInsert,
                             int index)

Inserts the given element at the given index to the existing array. The result is a new array that contains one more element.

Parameters:

array - The array to extend.

toInsert - The element to insert.

index - The index to insert the element at.

Returns:

The new created array with one more element.

contains

public static <T> boolean contains(T[] array,
                                   T toSearch)

Checks if the given array contains the element to search.

Type Parameters:

T - The type of the array.

Parameters:

array - The array.

toSearch - The element to search.

Returns:

true if the array contains the element or false if not or if the array is null.

contains

public static <T> boolean contains(T[] array,
                                   T toSearch,
                                   java.util.Comparator<T> comparator)

Checks if the given array contains the element to search. The equality is computed via the comparator. Objects are equal if the comparison result is 0.

Type Parameters:

T - The type of the array.

Parameters:

array - The array.

toSearch - The element to search.

comparator - the Comparator to use.

Returns:

true if the array contains the element or false if not or if the array is null.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

indexOf

public static <T> int indexOf(T[] array,
                              T toSearch)

Returns the first index in the given array that contains the element to search.

Parameters:

array - The array to search in.

toSearch - The element to search.

Returns:

The first index in the array that contains the element to search or -1 if the elment is not containd in the array.

indexOf

public static <T> int indexOf(T[] array,
                              T toSearch,
                              java.util.Comparator<T> comparator)

Returns the first index in the given array that contains the element to search. The equality is computed via the comparator. Objects are equal if the comparison result is 0.

Parameters:

array - The array to search in.

toSearch - The element to search.

comparator - the Comparator to use.

Returns:

The first index in the array that contains the element to search or -1 if the elment is not containd in the array.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

remove

public static <T> T[] remove(T[] array,
                             T toRemove)

Removes all occurrences from toRemove in the array. The equality is computed via ObjectUtil.equals(Object, Object).

Parameters:

array - The array to remove from.

toRemove - The element to remove.

Returns:

A copy of the array without the element toRemove or null if the given array was null.

remove

public static <T> T[] remove(T[] array,
                             T toRemove,
                             java.util.Comparator<T> comparator)

Removes all occurrences from toRemove in the array. The equality is computed via the comparator. Objects are equal if the comparison result is 0.

Parameters:

array - The array to remove from.

toRemove - The element to remove.

comparator - The Comparator to use.

Returns:

A copy of the array without the element toRemove or null if the given array was null.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

toString

public static <T> java.lang.String toString(T... array)

Converts the given array into a String. For each element is Object.toString() used to convert it into a String.

Parameters:

array - The array to convert.

Returns:

The array as String.

toString

public static <T> java.lang.String toString(T[] array,
                                            java.lang.String separator)

Converts the given array into a String. For each element is Object.toString() used to convert it into a String.

Parameters:

array - The array to convert.

separator - The separator between to array elements.

Returns:

The array as String.

toString

public static java.lang.String toString(int[] array)

Converts the given array into a String.

Parameters:

array - The array to convert.

Returns:

The array as String.

toString

public static java.lang.String toString(int[] array,
                                        java.lang.String separator)

Converts the given array into a String.

Parameters:

array - The array to convert.

separator - The separator between to array elements.

Returns:

The array as String.

isEmpty

public static <T> boolean isEmpty(T[] array)

Checks if the given array is empty.

Parameters:

array - The array to check.

Returns:

true array is empty or null, false array is not empty.

getPrevious

public static <T> T getPrevious(T[] array,
                                T toSearch)

Returns the previous element if available from the array.

Parameters:

array - The array to search in.

toSearch - The element for that the previous one is needed.

Returns:

The previous element or null if no element was found.

getPrevious

public static <T> T getPrevious(T[] array,
                                T toSearch,
                                java.util.Comparator<T> comparator)
                         throws java.lang.IllegalArgumentException

Returns the previous element if available from the array. The equality is computed via the comparator. Objects are equal if the comparison result is 0.

Parameters:

array - The array to search in.

toSearch - The element for that the previous one is needed.

comparator - the Comparator to use.

Returns:

The previous element or null if no element was found.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

getFollowing

public static <T> T getFollowing(T[] array,
                                 T toSearch)

Returns the following element if available from the array.

Parameters:

array - The array to search in.

toSearch - The element for that the following one is needed.

Returns:

The following element or null if no element was found.

getFollowing

public static <T> T getFollowing(T[] array,
                                 T toSearch,
                                 java.util.Comparator<T> comparator)
                          throws java.lang.IllegalArgumentException

Returns the following element if available from the array. The equality is computed via the comparator. Objects are equal if the comparison result is 0.

Parameters:

array - The array to search in.

toSearch - The element for that the following one is needed.

comparator - the Comparator to use.

Returns:

The following element or null if no element was found.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

isLast

public static <T> boolean isLast(T[] array,
                                 T toSearch)

Checks if the given element is the last element in the array.

Type Parameters:

T - The type of the array.

Parameters:

array - The array.

toSearch - The element to search.

Returns:

true is last element, false is not last element or even not contained in the array.

isLast

public static <T> boolean isLast(T[] array,
                                 T toSearch,
                                 java.util.Comparator<T> comparator)

Checks if the given element is the last element in the array. Objects are equal if the comparison result is 0.

Type Parameters:

T - The type of the array.

Parameters:

array - The array.

toSearch - The element to search.

comparator - the Comparator to use.

Returns:

true is last element, false is not last element or even not contained in the array.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

isFirst

public static <T> boolean isFirst(T[] array,
                                  T toSearch)

Checks if the given element is the first element in the array.

Type Parameters:

T - The type of the array.

Parameters:

array - The array.

toSearch - The element to search.

Returns:

true is first element, false is not first element or even not contained in the array.

isFirst

public static <T> boolean isFirst(T[] array,
                                  T toSearch,
                                  java.util.Comparator<T> comparator)

Checks if the given element is the first element in the array. Objects are equal if the comparison result is 0.

Type Parameters:

T - The type of the array.

Parameters:

array - The array.

toSearch - The element to search.

comparator - the Comparator to use.

Returns:

true is first element, false is not first element or even not contained in the array.

Throws:

java.lang.IllegalArgumentException - If the comparator is null.

getFirst

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

Returns the first element from the given array.

Parameters:

array - The array to get first element from.

Returns:

The first element or null if no element is available.

getLast

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

Returns the last element from the given array.

Parameters:

array - The array to get last element from.

Returns:

The first element or null if no element is available.

generatePermutations

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

Computes all permutations of the given array using the 'Heap's algorithm'.

Parameters:

array - The array to generate its permutations.

Returns:

The generated permutations or null if the given array is null.

See Also:

https://en.wikipedia.org/wiki/Heap's_algorithm

generatePermutations

private static <T> int generatePermutations(T[] array,
                                            int n,
                                            T[][] permutations,
                                            int permutationsIndex)

Recursive implementation of the 'Heap's algorithm':

 procedure generate(n : integer, A : array of any):
    if n = 1 then
       output(A)
    else
       for i := 0; i < n; i += 1 do
          generate(n - 1, A)
          if n is even then
             swap(A[i], A[n-1])
          else
             swap(A[0], A[n-1])
          end if
       end for
    end if
 

Parameters:

array - The array to generate its permutations.

n - The recursive termination criterion.

permutations - The result List to fill.

Returns:

The next index in permutations to fill.

See Also:

https://en.wikipedia.org/wiki/Heap's_algorithm