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      Java Arrays - Class

      Java Tutorial

      This Java tutorial is tailored for newcomers, offering a journey from basic principles to complex Java programming techniques. Completing this tutorial equips you with a solid understanding of Java, preparing you for advanced learning. You'll emerge ready to tackle the challenges of becoming a top-tier software engineer, with the skills to innovate and excel in the vast world of software development.

      Arrays Class | Array Methods

      Introduction

      The Java Arrays class contains a static factory that allows arrays to be viewed as lists. Following are the important points about Arrays
      • This class contains various methods for manipulating arrays (such as sorting and searching).
      • The methods in this class throw a NullPointerException if the specified array reference is null.

      Arrays Class Declaration

      Following is the declaration for java.util.Arrays class 
      public class Arrays
         extends Object

      Arrays Class Methods

      Sr.No.
      Method & Description
      1
      static <T> List<T> asList(T... a)
      This method returns a fixed-size list backed by the specified array.
      2
      static int binarySearch(byte[] a, byte key)
      This method searches the specified array of bytes for the specified value using the binary search algorithm.
      3
      static int binarySearch(char[] a, char key)
      This method searches the specified array of chars for the specified value using the binary search algorithm.
      4
      static int binarySearch(double[] a, double key)
      This method searches the specified array of doubles for the specified value using the binary search algorithm.
      5
      static int binarySearch(float[] a, float key)
      This method searches the specified array of floats for the specified value using the binary search algorithm.
      6
      static int binarySearch(int[] a, int key)
      This method searches the specified array of ints for the specified value using the binary search algorithm.
      7
      static int binarySearch(long[] a, int fromIndex, int toIndex, long key)
      This method searches a range of the specified array of longs for the specified value using the binary search algorithm.
      8
      static int binarySearch(Object[] a, Object key)
      This method searches the specified array for the specified object using the binary search algorithm.
      9
      static int binarySearch(short[] a, short key)
      This method searches the specified array of shorts for the specified value using the binary search algorithm.
      10
      static <T> int binarySearch(T[] a, T key, Comparator<? super T> c)
      This method searches the specified array for the specified object using the binary search algorithm.
      11
      static int compare(boolean[] a, boolean[] b)
      This method compares two boolean arrays lexicographically.
      12
      static int compare(byte[] a, byte[] b)
      This method compares two byte arrays lexicographically.
      13
      static int compare(char[] a, char[] b)
      This method compares two char arrays lexicographically.
      14
      static int compare(double[] a, double[] b)
      This method compares two double arrays lexicographically.
      15
      static int compare(float[] a, float[] b)
      This method compares two float arrays lexicographically.
      16
      static int compare(int[] a, int[] b)
      This method compares two int arrays lexicographically.
      17
      static int compare(long[] a, long[] b)
      This method compares two long arrays lexicographically.
      18
      static int compare(short[] a, short[] b)
      This method compares two short arrays lexicographically.
      19
      static int compare(T[] a, T[] b)
      This method compares two Object arrays lexicographically.
      20
      compareUnsigned(byte[] a, byte[] b)
      This method compares two byte arrays lexicographically, numerically treating elements as unsigned.
      21
      compareUnsigned(int[] a, int[] b)
      This method compares two int arrays lexicographically, numerically treating elements as unsigned.
      22
      compareUnsigned(long[] a, long[] b)
      This method compares two long arrays lexicographically, numerically treating elements as unsigned.
      23
      compareUnsigned(short[] a, short[] b)
      This method compares two short arrays lexicographically, numerically treating elements as unsigned.
      24
      static boolean[] copyOf(boolean[] original, int newLength)
      This method copies the specified array, truncating or padding with false (if necessary) so the copy has the specified length.
      25
      static byte[] copyOf(byte[] original, int newLength)
      This method copies the specified array, truncating or padding with false (if necessary) so the copy has the specified length.
      26
      static char[] copyOf(char[] original, int newLength)
      This method copies the specified array, truncating or padding with false (if necessary) so the copy has the specified length.
      27
      static double[] copyOf(double[] original, int newLength)
      This method copies the specified array, truncating or padding with false (if necessary) so the copy has the specified length.
      28
      static float[] copyOf(float[] original, int newLength)
      This method copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
      29
      static int[] copyOf(int[] original, int newLength)
      This method copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
      30
      static long[] copyOf(long[] original, int newLength)
      This method copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
      31
      static short[] copyOf(short[] original, int newLength)
      This method copies the specified array, truncating or padding with zeros (if necessary) so the copy has the specified length.
      32
      static <T> T[] copyOf(T[] original, int newLength)
      This method copies the specified array, truncating or padding with nulls (if necessary) so the copy has the specified length.
      33
      static <T, U> T[] copyOf(U[] original, int newLength,Class<? extends T[]> newType)
      This method copies the specified array, truncating or padding with nulls (if necessary) so the copy has the specified length.
      34
      static boolean[] copyOfRange(boolean[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      35
      static byte[] copyOfRange(byte[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      36
      static char[] copyOfRange(char[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      37
      static double[] copyOfRange(double[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      38
      static int[] copyOfRange(int[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      39
      static long[] copyOfRange(long[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      40
      static short[] copyOfRange(short[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      41
      static <T> T[] copyOfRange(T[] original, int from, int to)
      This method copies the specified range of the specified array into a new array.
      42
      static <T,U> T[] copyOfRange(U[] original, int from, int to, Class<? extends T[]> newType)
      This method copies the specified range of the specified array into a new array.
      43
      static boolean deepEquals(Object[] a1, Object[] a2)
      This method returns true if the two specified arrays are deeply equal to one another.
      44
      static int deepHashCode(Object[] a)
      This method returns a hash code based on the "deep contents" of the specified array.
      45
      static String deepToString(Object[] a)
      This method returns a string representation of the "deep contents" of the specified array.
      46
      static boolean equals(boolean[] a, boolean[] a2)
      This method returns true if the two specified arrays of booleans are equal to one another.
      47
      static boolean equals(byte[] a, byte[] a2)
      This method returns true if the two specified arrays of bytes are equal to one another.
      48
      static boolean equals(char[] a, char[] a2)
      This method returns true if the two specified arrays of chars are equal to one another.
      49
      static boolean equals(double[] a, double[] a2)
      This method returns true if the two specified arrays of double are equal to one another.
      50
      static boolean equals(float[] a, float[] a2)
      This method returns true if the two specified arrays of floats are equal to one another.
      51
      static boolean equals(int[] a, int[] a2)
      This method returns true if the two specified arrays of ints are equal to one another.
      52
      static boolean equals(long[] a, long[] a2)
      This method returns true if the two specified arrays of longs are equal to one another.
      53
      static boolean equals(short[] a, short[] a2)
      This method returns true if the two specified arrays of shorts are equal to one another.
      54
      static boolean equals(Object[] a, Object[] a2)
      This method returns true if the two specified arrays of Objects are equal to one another.
      55
      static boolean equals(T[] a, T[] a2, Comparator<? super T> cmp)
      This method returns true if the two specified arrays of Objects are equal to one another.
      56
      static void fill(boolean[] a, boolean val)
      This method assigns the specified boolean value to each element of the specified array of booleans.
      57
      static void fill(byte[] a, byte val)
      This method assigns the specified byte value to each element of the specified array of bytes.
      58
      static void fill(char[] a, char val)
      This method assigns the specified char value to each element of the specified array of chars.
      59
      static void fill(double[] a, double val)
      This method assigns the specified double value to each element of the specified array of doubles.
      60
      static void fill(float[] a, float val)
      This method assigns the specified float value to each element of the specified array of floats.
      61
      static void fill(int[] a, int val)
      This method assigns the specified int value to each element of the specified array of ints.
      62
      static void fill(long[] a, long val)
      This method assigns the specified long value to each element of the specified array of longs.
      63
      static void fill(Object[] a, Object val)
      This method assigns the specified Object reference to each element of the specified array of Objects.
      64
      static void fill(short[] a, short val)
      This method assigns the specified short value to each element of the specified array of shorts.
      65
      static int hashCode(boolean[] a)
      This method returns a hash code based on the contents of the specified array.
      66
      static int mismatch(boolean[] a, boolean[] b)
      This method finds and returns the index of the first mismatch between two boolean arrays, otherwise return -1 if no mismatch is found.
      67
      static int mismatch(byte[] a, byte[] b)
      This method finds and returns the index of the first mismatch between two byte arrays, otherwise return -1 if no mismatch is found.
      68
      static int mismatch(char[] a, char[] b)
      This method finds and returns the index of the first mismatch between two char arrays, otherwise return -1 if no mismatch is found.
      69
      static int mismatch(double[] a, double[] b)
      This method finds and returns the index of the first mismatch between two double arrays, otherwise return -1 if no mismatch is found.
      70
      static int mismatch(int[] a, int[] b)
      This method finds and returns the index of the first mismatch between two int arrays, otherwise return -1 if no mismatch is found.
      71
      static int mismatch(long[] a, long[] b)
      This method finds and returns the index of the first mismatch between two long arrays, otherwise return -1 if no mismatch is found.
      72
      static int mismatch(short[] a, short[] b)
      This method finds and returns the index of the first mismatch between two short arrays, otherwise return -1 if no mismatch is found.
      73
      static int mismatch(Object[] a, Object[] b)
      This method finds and returns the index of the first mismatch between two object arrays, otherwise return -1 if no mismatch is found.
      74
      static int mismatch(T[] a, T[] b, Comparator<? super T> cmp)
      This method finds and returns the index of the first mismatch between two object arrays, otherwise return -1 if no mismatch is found.
      75
      static void parallelPrefix(double[] array, DoubleBinaryOperator op)
      This method cumulates, in parallel, each element of the given array in place, using the supplied function.
      76
      static void parallelPrefix(int[] array, IntBinaryOperator op)
      This method cumulates, in parallel, each element of the given array in place, using the supplied function.
      77
      static void parallelPrefix(long[] array, LongBinaryOperator op)
      This method cumulates, in parallel, each element of the given array in place, using the supplied function.
      78
      static <T> void parallelPrefix(T[] array, BinaryOperator<T> op)
      This method cumulates, in parallel, each element of the given array in place, using the supplied function.
      79
      static void parallelSetAll(double[] array, IntToDoubleFunction generator)
      This method sets all elements of the specified array, in parallel, using the provided generator function to compute each element.
      80
      static void parallelSetAll(int[] array, IntUnaryOperator generator)
      This method sets all elements of the specified array, in parallel, using the provided generator function to compute each element.
      81
      static void parallelSetAll(long[] array, IntToLongFunction generator)
      This method sets all elements of the specified array, in parallel, using the provided generator function to compute each element.
      82
      static <T> void parallelSetAll(T[] array, IntFunction<? extends T> generator)
      This method sets all elements of the specified array, in parallel, using the provided generator function to compute each element.
      83
      static void parallelSort(byte[] a)
      This method sorts the specified array of bytes into ascending numerical order.
      84
      static void parallelSort(char[] a)
      This method sorts the specified array of chars into ascending numerical order.
      85
      static void parallelSort(double[] a)
      This method sorts the specified array of doubles into ascending numerical order.
      86
      static void parallelSort(float[] a)
      This method sorts the specified array of floats into ascending numerical order.
      87
      static void parallelSort(int[] a)
      This method sorts the specified array of ints into ascending numerical order.
      88
      static void parallelSort(long[] a)
      This method sorts the specified array of longs into ascending numerical order.
      89
      static void parallelSort(short[] a)
      This method sorts the specified array of shorts into ascending numerical order.
      90
      static <T extends Comparable<? super T>> void parallelSort(T[] a)
      This method sorts the specified array of objects into ascending order, according to the natural ordering of its elements.
      91
      static <T>> void parallelSort(T[] a, Comparator<? super T> cmp)
      This method sorts the specified array of objects into ascending order, according to the ordering provided by the Comparator instance.
      92
      static void setAll(double[] array, IntToDoubleFunction generator)
      This method sets all elements of the specified array, using the provided generator function to compute each element.
      93
      static void setAll(int[] array, IntUnaryOperator generator)
      This method sets all elements of the specified array, using the provided generator function to compute each element.
      94
      static void setAll(long[] array, IntToLongFunction generator)
      This method sets all elements of the specified array, using the provided generator function to compute each element.
      95
      static <T> void setAll(T[] array, IntFunction<? extends T> generator)
      This method sets all elements of the specified array, using the provided generator function to compute each element.
      96
      static Spliterator.OfDouble spliterator(double[] array)
      This method returns a Spliterator.OfDouble covering all of the specified array.
      97
      static Spliterator.OfInt spliterator(int[] array)
      This method returns a Spliterator.OfInt covering all of the specified array.
      98
      static Spliterator.OfLong spliterator(long[] array)
      This method returns a Spliterator.OfLong covering all of the specified array.
      99
      static <T> Spliterator<T> spliterator(T[] array)
      This method returns a Spliterator covering all of the specified array.
      100
      static DoubleStream stream(double[] array)
      This method returns a sequential DoubleStream with the specified array as its source.
      101
      static IntStream stream(int[] array)
      This method returns a sequential IntStream with the specified array as its source.
      102
      static LongStream stream(long[] array)
      This method returns a sequential LongStream with the specified array as its source.
      103
      static <T> Stream<T> stream(T[] array)
      This method returns a sequential Stream with the specified array as its source.
      104
      static void sort(byte[] a)
      This method sorts the specified array of bytes into ascending numerical order.
      105
      static void sort(char[] a)
      This method sorts the specified array of chars into ascending numerical order.
      106
      static void sort(double[] a)
      This method sorts the specified array of doubles into ascending numerical order.
      107
      static void sort(float[] a)
      This method sorts the specified array of floats into ascending numerical order.
      108
      static void sort(int[] a)
      This method sorts the specified array of ints into ascending numerical order.
      109
      static void sort(long[] a)
      This method sorts the specified array of longs into ascending numerical order.
      110
      static void sort(Object[] a)
      This method sorts the specified array of objects into ascending order, according to the natural ordering of its elements.
      111
      static void sort(short[] a)
      This method sorts the specified array of shorts into ascending numerical order.
      112
      static <T> void sort(T[] a, Comparator<? super T> c)
      This method sorts the specified array of objects according to the order induced by the specified comparator.
      113
      static String toString(boolean[] a)
      This method returns a string representation of the contents of the specified array of boolean.

      Methods Inherited

      This class inherits methods from the following classes
      • java.util.Object

      Arrays Class Example

      This Java example demonstrates the binarySearch() method of Arrays class.
      // Importing the Arrays class
      import java.util.Arrays;
      
      // Public Main Class
      public class Main {
        public static void main(String[] args) {
          // Declaring an array
          int arr[] = {8, 5, 3, 10, 2, 1, 15, 20};
      
          // Sorting the array
          Arrays.sort(arr);
      
          // Taking an element to search
          int ele = 15;
      
          // Using binarySearch() method to search "ele"
          System.out.println(
            ele + " presents at the index = " +
            Arrays.binarySearch(arr, ele));
        }
      }
      Let us compile and run the above program, this will produce the following result 
      15 presents at the index = 6