ch.jalu.typeresolver.array

Class ArrayUtils

java.lang.Object

ch.jalu.typeresolver.array.ArrayUtils

public final class ArrayUtils
extends Object

This class contains methods that can handle arrays of any type (boolean[], byte[], Object[], etc.). Most methods delegate to methods in Arrays with the appropriate signature. The methods in this class are useful when dealing with arrays held as Object variable whose specific array type is unknown.

Methods throw a runtime exception if the given object is not an array. To check if an object is an array, use object.getClass().isArray(). See individual methods for specific caveats.

Method Summary

Modifier and Type	Method and Description
static int	binarySearch(Object array, int fromIndex, int toIndex, Object key) Delegates to the appropriate method for binary search and returns the result.
static int	binarySearch(Object array, Object key) Delegates to the appropriate method for binary search and returns the result.
static Object	copyOf(Object original, int newLength) Delegates to the appropriate method for creating a copy and returns the result.
static Object	copyOfRange(Object original, int from, int to) Delegates to the appropriate method for creating a copy of a range and returns the result.
static boolean	equals(Object a, Object a2) Delegates to the appropriate method for checking whether two arrays have the same entries, and returns the result.
static void	fill(Object a, int fromIndex, int toIndex, Object val) Delegates to the appropriate method for filling an array with the given value.
static void	fill(Object a, Object val) Delegates to the appropriate method for filling an array with the given value.
static int	hashCode(Object a) Delegates to the appropriate method for calculating the hash code, and returns the result.
static void	parallelSort(Object a) Delegates to the appropriate method to parallel-sort the given array.
static void	parallelSort(Object a, int fromIndex, int toIndex) Delegates to the appropriate method to parallel-sort the given array.
static int	simpleBooleanArrayBinarySearch(boolean[] array, int fromIndex, int toIndex, boolean value) Fill-in implementation for a boolean array binary search: allows to search for a value in a boolean array that has been sorted.
static void	simpleBooleanArraySort(boolean[] array, int fromIndex, int toIndex) Naive implementation of an array sort for boolean arrays.
static void	sort(Object a) Delegates to the appropriate method to sort the given array.
static void	sort(Object a, int fromIndex, int toIndex) Delegates to the appropriate method to sort the given array.
static Stream<Object>	stream(Object array) Returns a stream of the objects in the given array.
static String	toString(Object a) Delegates to the appropriate method to generate a String representation of the given array.

Methods inherited from class java.lang.Object

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

Method Detail

binarySearch

public static int binarySearch(Object array,
                               Object key)

Delegates to the appropriate method for binary search and returns the result. Depending on the array type, this method calls Arrays.binarySearch(byte[], int, int, byte), Arrays.binarySearch(char[], int, int, char), etc. An exception is thrown if the key does not correspond to the array type, or if it is null. All elements in Object[] arrays must implement Comparable and be mutually comparable, or an exception will be thrown.

There is no binary search for boolean arrays in Arrays. This class provides a fill-in implementation.

Parameters:

array - the array object (e.g. String[] or double[])

key - the key to search for (must match the array type and may not be null)

Returns:

index of the key, or a negative insertion point (refer to Arrays.binarySearch(byte[], byte))

binarySearch

public static int binarySearch(Object array,
                               int fromIndex,
                               int toIndex,
                               Object key)

Delegates to the appropriate method for binary search and returns the result. Depending on the array type, this method calls Arrays.binarySearch(byte[], int, int, byte), Arrays.binarySearch(char[], int, int, char), etc. An exception is thrown if the key does not correspond to the array type, or if it is null. All elements in Object[] arrays must implement Comparable, and be mutually comparable, or an exception will be thrown.

There is no binary search for boolean arrays in Arrays. This class provides a fill-in implementation.

Parameters:

array - the array object (e.g. String[] or double[])

fromIndex - start index of the range to search in (inclusive)

toIndex - end index of the range to search in (exclusive)

key - the key to search for (must match the array type and may not be null)

Returns:

index of the key, or a negative insertion point (refer to Arrays.binarySearch(byte[], byte))

copyOf

public static Object copyOf(Object original,
                            int newLength)

Delegates to the appropriate method for creating a copy and returns the result. Depending on the array type, this method calls Arrays.copyOf(byte[], int), Arrays.copyOf(char[], int), etc.

Parameters:

original - the array object to copy (e.g. String[] or double[])

newLength - the length of the copy

Returns:

copied array of the same type as the original

copyOfRange

public static Object copyOfRange(Object original,
                                 int from,
                                 int to)

Delegates to the appropriate method for creating a copy of a range and returns the result. Depending on the array type, this method calls Arrays.copyOfRange(byte[], int, int), Arrays.copyOfRange(char[], int, int), etc.

Parameters:

original - the array object to copy (e.g. String[] or double[])

from - start index of the range to copy (inclusive)

to - end index of the range to copy (exclusive)

Returns:

copy of the specified range, of the same type as the original

equals

public static boolean equals(Object a,
                             Object a2)

Delegates to the appropriate method for checking whether two arrays have the same entries, and returns the result. Depending on the array type, this method calls Arrays.equals(byte[], byte[]), Arrays.equals(char[], char[]), etc.

Parameters:

a - the array to check for equality (e.g. String[] or double[])

a2 - the array to check the first array with (must have the same type)

Returns:

whether the two arrays are equal

fill

public static void fill(Object a,
                        Object val)

Delegates to the appropriate method for filling an array with the given value. Depending on the array type, this method calls Arrays.fill(byte[], int, int, byte), Arrays.fill(char[], int, int, char), etc.

Parameters:

a - the array to fill (e.g. String[] or double[])

val - the value to fill the array with

fill

public static void fill(Object a,
                        int fromIndex,
                        int toIndex,
                        Object val)

Delegates to the appropriate method for filling an array with the given value. Depending on the array type, this method calls Arrays.fill(byte[], int, int, byte), Arrays.fill(char[], int, int, char), etc.

Parameters:

a - the array to fill (e.g. String[] or double[])

fromIndex - start index of the range to fill with the value (inclusive)

toIndex - end index of the range to fill with the value (exclusive)

val - the value to fill the array with

hashCode

public static int hashCode(Object a)

Delegates to the appropriate method for calculating the hash code, and returns the result. Depending on the array type, this method calls Arrays.hashCode(byte[]), Arrays.hashCode(char[]), etc.

Parameters:

a - the array to process (e.g. String[] or double[])

Returns:

hash code for the array

parallelSort

public static void parallelSort(Object a)

Delegates to the appropriate method to parallel-sort the given array. Depending on the array type, this method calls Arrays.parallelSort(byte[], int, int), Arrays.parallelSort(char[], int, int), etc.

The sorting of Object[] arrays is delegated to Arrays.parallelSort(Comparable[], int, int), which requires the array component to implement Comparable. All elements must be mutually comparable. An exception is thrown otherwise.

There is no sorting method for boolean arrays in Arrays. This class provides a fill-in implementation, which does not perform the search in parallel. Developers requiring more efficient sorting of boolean arrays are suggested to use another method.

Parameters:

a - the array to sort (e.g. String[] or double[])

parallelSort

public static void parallelSort(Object a,
                                int fromIndex,
                                int toIndex)

Delegates to the appropriate method to parallel-sort the given array. Depending on the array type, this method calls Arrays.parallelSort(byte[], int, int), Arrays.parallelSort(char[], int, int), etc.

The sorting of Object[] arrays is delegated to Arrays.parallelSort(Comparable[], int, int), which requires the array component to implement Comparable. All elements must be mutually comparable. An exception is thrown otherwise.

There is no sorting method for boolean arrays in Arrays. This class provides a fill-in implementation, which does not perform the search in parallel. Developers requiring more efficient sorting of boolean arrays are suggested to use another method.

Parameters:

a - the array to sort (e.g. String[] or double[])

fromIndex - start index (inclusive) of the range that should be sorted

toIndex - end index (exclusive) of the range that should be sorted

stream

public static Stream<Object> stream(Object array)

Returns a stream of the objects in the given array. Because the streaming methods in Arrays, such as Arrays.stream(int[]), return different types of streams, this method returns an object stream which is constructed by getting the elements of the array by index.

It may be more efficient to handle array types individually with their respective stream types when performance is crucial.

Parameters:

array - the array to stream over

Returns:

stream of the array's elements (as reference types)

sort

public static void sort(Object a)

Delegates to the appropriate method to sort the given array. Depending on the array type, this method calls Arrays.sort(byte[], int, int), Arrays.sort(char[], int, int), etc.

The sorting of Object[] arrays is delegated to Arrays.sort(Object[], int, int), which requires that all elements implement Comparable and that they be mutually comparable. An exception is thrown otherwise.

There is no sorting method for boolean arrays in Arrays. This class provides a fill-in implementation. Developers requiring more efficient sorting of boolean arrays are suggested to use another implementation.

Parameters:

a - the array to sort (e.g. String[] or double[])

sort

public static void sort(Object a,
                        int fromIndex,
                        int toIndex)

Delegates to the appropriate method to sort the given array. Depending on the array type, this method calls Arrays.sort(byte[], int, int), Arrays.sort(char[], int, int), etc.

The sorting of Object[] arrays is delegated to Arrays.sort(Object[], int, int), which requires that all elements implement Comparable and that they be mutually comparable. An exception is thrown otherwise.

There is no sorting method for boolean arrays in Arrays. This class provides a fill-in implementation. Developers requiring more efficient sorting of boolean arrays are suggested to use another implementation.

Parameters:

a - the array to sort (e.g. String[] or double[])

fromIndex - start index (inclusive) of the range that should be sorted

toIndex - end index (exclusive) of the range that should be sorted

toString

public static String toString(Object a)

Delegates to the appropriate method to generate a String representation of the given array. Depending on the array type, this method calls Arrays.toString(byte[]), Arrays.toString(char[]), etc.

Parameters:

a - the array to sort (e.g. String[] or double[])

Returns:

toString of the array

simpleBooleanArrayBinarySearch

public static int simpleBooleanArrayBinarySearch(boolean[] array,
                                                 int fromIndex,
                                                 int toIndex,
                                                 boolean value)

Fill-in implementation for a boolean array binary search: allows to search for a value in a boolean array that has been sorted. The result is the index in the array of a matching value (no guarantee which index it is if there are multiple matching values). If the value could not be matched, a negative number is returned as described in binary search methods of Arrays (e.g. Arrays.binarySearch(char[], int, int, char)).

Parameters:

array - the boolean array to search in

fromIndex - the start index (inclusive) of the range to search in

toIndex - the end index (exclusive) of the range to search in

value - the value to search for

Returns:

the matched index, or the "insertion index" as a negative number (see Arrays.binarySearch(char[], int, int, char))

simpleBooleanArraySort

public static void simpleBooleanArraySort(boolean[] array,
                                          int fromIndex,
                                          int toIndex)

Naive implementation of an array sort for boolean arrays. Sorts the entries of the array in the specified range.

Background: Arrays has methods for sorting all array types (e.g. Arrays.sort(byte[], int, int)) except for boolean arrays.

Parameters:

array - the array to sort

fromIndex - the start index (inclusive) of the range that should be sorted

toIndex - the end index (exclusive) of the range that should be sorted