Added in API level 19

Objects

class Objects
kotlin.Any
   ↳ java.util.Objects

This class consists of static utility methods for operating on objects, or checking certain conditions before operation. These utilities include null-safe or null-tolerant methods for computing the hash code of an object, returning a string for an object, comparing two objects, and checking if indexes or sub-range values are out of bounds.

Summary

Public methods
static Int
checkFromIndexSize(fromIndex: Int, size: Int, length: Int)

Checks if the sub-range from fromIndex (inclusive) to fromIndex + size (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).
static Long
checkFromIndexSize(fromIndex: Long, size: Long, length: Long)

Checks if the sub-range from fromIndex (inclusive) to fromIndex + size (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).
static Int
checkFromToIndex(fromIndex: Int, toIndex: Int, length: Int)

Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).
static Long
checkFromToIndex(fromIndex: Long, toIndex: Long, length: Long)

Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).
static Int
checkIndex(index: Int, length: Int)

Checks if the index is within the bounds of the range from 0 (inclusive) to length (exclusive).
static Long
checkIndex(index: Long, length: Long)

Checks if the index is within the bounds of the range from 0 (inclusive) to length (exclusive).
static Int
compare(a: T, b: T, c: Comparator<in T>)

{@return 0 if the arguments are identical and {@code * c.
static Boolean
deepEquals(a: Any?, b: Any?)

{@return {@code true} if the arguments are deeply equal to each other * and {@code false} otherwise} Two null values are deeply equal.
static Boolean
equals(a: Any?, b: Any?)

{@return {@code true} if the arguments are equal to each other * and {@code false} otherwise} Consequently, if both arguments are null, true is returned.
static Int
hash(vararg values: Any!)

{@return a hash code for a sequence of input values} The hash code is generated as if all the input values were placed into an array, and that array were hashed by calling Arrays.hashCode(Object[]).
static Int

{@return the hash code of a non-{@code null} argument and 0 for * a {@code null} argument}
static Boolean
isNull(obj: Any?)

{@return {@code true} if the provided reference is {@code * null}; {@code false} otherwise}
static Boolean
nonNull(obj: Any?)

{@return {@code true} if the provided reference is non-{@code null}; * {@code false} otherwise}
static T
requireNonNull(obj: T?)

Checks that the specified object reference is not null.
static T
requireNonNull(obj: T?, message: String)

Checks that the specified object reference is not null and throws a customized NullPointerException if it is.
static T
requireNonNull(obj: T?, messageSupplier: Supplier<String!>)

Checks that the specified object reference is not null and throws a customized NullPointerException if it is.
static T
requireNonNullElse(obj: T?, defaultObj: T)

{@return the first argument if it is non-{@code null} and * otherwise the second argument if it is non-{@code null}}
static T
requireNonNullElseGet(obj: T?, supplier: Supplier<out T>)

{@return the first argument if it is non-{@code null} and * otherwise the value from {@code supplier.
static String

{@return a string equivalent to the string returned by {@code * Object.
static String

{@return the result of calling {@code toString} for a * non-{@code null} argument and {@code "null"} for a * {@code null} argument}
static String
toString(o: Any?, nullDefault: String)

{@return the result of calling {@code toString} on the first * argument if the first argument is not {@code null} and the * second argument otherwise}

Public methods

checkFromIndexSize

Added in API level 30
static fun checkFromIndexSize(
    fromIndex: Int, 
    size: Int, 
    length: Int
): Int

Checks if the sub-range from fromIndex (inclusive) to fromIndex + size (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).

The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • size < 0
  • fromIndex + size > length, taking into account integer overflow
  • length < 0, which is implied from the former inequalities
Parameters
fromIndex Int: the lower-bound (inclusive) of the sub-interval
size Int: the size of the sub-range
length Int: the upper-bound (exclusive) of the range
Return
Int fromIndex if the sub-range within bounds of the range
Exceptions
java.lang.IndexOutOfBoundsException if the sub-range is out of bounds

checkFromIndexSize

Added in API level 34
static fun checkFromIndexSize(
    fromIndex: Long, 
    size: Long, 
    length: Long
): Long

Checks if the sub-range from fromIndex (inclusive) to fromIndex + size (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).

The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • size < 0
  • fromIndex + size > length, taking into account integer overflow
  • length < 0, which is implied from the former inequalities
Parameters
fromIndex Long: the lower-bound (inclusive) of the sub-interval
size Long: the size of the sub-range
length Long: the upper-bound (exclusive) of the range
Return
Long fromIndex if the sub-range within bounds of the range
Exceptions
java.lang.IndexOutOfBoundsException if the sub-range is out of bounds

checkFromToIndex

Added in API level 30
static fun checkFromToIndex(
    fromIndex: Int, 
    toIndex: Int, 
    length: Int
): Int

Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).

The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • fromIndex > toIndex
  • toIndex > length
  • length < 0, which is implied from the former inequalities
Parameters
fromIndex Int: the lower-bound (inclusive) of the sub-range
toIndex Int: the upper-bound (exclusive) of the sub-range
length Int: the upper-bound (exclusive) the range
Return
Int fromIndex if the sub-range within bounds of the range
Exceptions
java.lang.IndexOutOfBoundsException if the sub-range is out of bounds

checkFromToIndex

Added in API level 34
static fun checkFromToIndex(
    fromIndex: Long, 
    toIndex: Long, 
    length: Long
): Long

Checks if the sub-range from fromIndex (inclusive) to toIndex (exclusive) is within the bounds of range from 0 (inclusive) to length (exclusive).

The sub-range is defined to be out of bounds if any of the following inequalities is true:

  • fromIndex < 0
  • fromIndex > toIndex
  • toIndex > length
  • length < 0, which is implied from the former inequalities
Parameters
fromIndex Long: the lower-bound (inclusive) of the sub-range
toIndex Long: the upper-bound (exclusive) of the sub-range
length Long: the upper-bound (exclusive) the range
Return
Long fromIndex if the sub-range within bounds of the range
Exceptions
java.lang.IndexOutOfBoundsException if the sub-range is out of bounds

checkIndex

Added in API level 30
static fun checkIndex(
    index: Int, 
    length: Int
): Int

Checks if the index is within the bounds of the range from 0 (inclusive) to length (exclusive).

The index is defined to be out of bounds if any of the following inequalities is true:

  • index < 0
  • index >= length
  • length < 0, which is implied from the former inequalities
Parameters
index Int: the index
length Int: the upper-bound (exclusive) of the range
Return
Int index if it is within bounds of the range
Exceptions
java.lang.IndexOutOfBoundsException if the index is out of bounds

checkIndex

Added in API level 34
static fun checkIndex(
    index: Long, 
    length: Long
): Long

Checks if the index is within the bounds of the range from 0 (inclusive) to length (exclusive).

The index is defined to be out of bounds if any of the following inequalities is true:

  • index < 0
  • index >= length
  • length < 0, which is implied from the former inequalities
Parameters
index Long: the index
length Long: the upper-bound (exclusive) of the range
Return
Long index if it is within bounds of the range
Exceptions
java.lang.IndexOutOfBoundsException if the index is out of bounds

compare

Added in API level 19
static fun <T : Any!> compare(
    a: T, 
    b: T, 
    c: Comparator<in T>
): Int

{@return 0 if the arguments are identical and {@code * c.compare(a, b)} otherwise} Consequently, if both arguments are null 0 is returned.

Note that if one of the arguments is null, a NullPointerException may or may not be thrown depending on what ordering policy, if any, the Comparator chooses to have for null values.

Parameters
<T> the type of the objects being compared
a T: an object
b T: an object to be compared with a
c Comparator<in T>: the Comparator to compare the first two arguments

deepEquals

Added in API level 19
static fun deepEquals(
    a: Any?, 
    b: Any?
): Boolean

{@return {@code true} if the arguments are deeply equal to each other * and {@code false} otherwise} Two null values are deeply equal. If both arguments are arrays, the algorithm in Arrays.deepEquals is used to determine equality. Otherwise, equality is determined by using the equals method of the first argument.

Parameters
a Any?: an object
b Any?: an object to be compared with a for deep equality

equals

Added in API level 19
static fun equals(
    a: Any?, 
    b: Any?
): Boolean

{@return {@code true} if the arguments are equal to each other * and {@code false} otherwise} Consequently, if both arguments are null, true is returned. Otherwise, if the first argument is not null, equality is determined by calling the equals method of the first argument with the second argument of this method. Otherwise, false is returned.

Parameters
a Any?: an object
b Any?: an object to be compared with a for equality

hash

Added in API level 19
static fun hash(vararg values: Any!): Int

{@return a hash code for a sequence of input values} The hash code is generated as if all the input values were placed into an array, and that array were hashed by calling Arrays.hashCode(Object[]).

This method is useful for implementing Object.hashCode() on objects containing multiple fields. For example, if an object that has three fields, x, y, and z, one could write: 

@Override public int hashCode() {
      return Objects.hash(x, y, z);
  }
Warning: When a single object reference is supplied, the returned value does not equal the hash code of that object reference. This value can be computed by calling hashCode(Object).
Parameters
values Any!: the values to be hashed

hashCode

Added in API level 19
static fun hashCode(o: Any?): Int

{@return the hash code of a non-{@code null} argument and 0 for * a {@code null} argument}

Parameters
o Any?: an object

isNull

Added in API level 24
static fun isNull(obj: Any?): Boolean

{@return {@code true} if the provided reference is {@code * null}; {@code false} otherwise}

Parameters
obj Any?: a reference to be checked against null

nonNull

Added in API level 24
static fun nonNull(obj: Any?): Boolean

{@return {@code true} if the provided reference is non-{@code null}; * {@code false} otherwise}

Parameters
obj Any?: a reference to be checked against null

requireNonNull

Added in API level 19
static fun <T : Any!> requireNonNull(obj: <