Package Summary  Overview Summary

class:Objects [CHANGED]

 
public final class Objects
extends Object
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.
API Note:
Static methods such as checkIndex(int, int) , checkFromToIndex(int, int, int) , and checkFromIndexSize(int, int, int) are provided for the convenience of checking if values corresponding to indexes and sub-ranges are out of bounds. Variations of these static methods support customization of the runtime exception, and corresponding exception detail message, that is thrown when values are out of bounds. Such methods accept a functional interface argument, instances of BiFunction, that maps out-of-bound values to a runtime exception. Care should be taken when using such methods in combination with an argument that is a lambda expression, method reference or class that capture values. In such cases the cost of capture, related to functional interface allocation, may exceed the cost of checking bounds.
Since:
1.7
 
public final class Objects
extends Object
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.
API Note:
Static methods such as checkIndex(int, int) , checkFromToIndex(int, int, int) , and checkFromIndexSize(int, int, int) are provided for the convenience of checking if values corresponding to indexes and sub-ranges are out of bounds. Variations of these static methods support customization of the runtime exception, and corresponding exception detail message, that is thrown when values are out of bounds. Such methods accept a functional interface argument, instances of BiFunction, that maps out-of-bound values to a runtime exception. Care should be taken when using such methods in combination with an argument that is a lambda expression, method reference or class that capture values. In such cases the cost of capture, related to functional interface allocation, may exceed the cost of checking bounds.
Since:
1.7
 
public final class Objects
extends Object
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.
Since:
1.7

method:equals(java.lang.Object,java.lang.Object) [NONE]

  • equals

    public static  boolean equals?(Object a, Object b)
    Returns true if the arguments are equal to each other and 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 - an object
    b - an object to be compared with a for equality
    Returns:
    true if the arguments are equal to each other and false otherwise
    See Also:
    Object.equals(Object)

    • method:deepEquals(java.lang.Object,java.lang.Object) [NONE]

    deepEquals

    public static  boolean deepEquals?(Object a, Object b)
    Returns true if the arguments are deeply equal to each other and 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 - an object
    b - an object to be compared with a for deep equality
    Returns:
    true if the arguments are deeply equal to each other and false otherwise
    See Also:
    Arrays.deepEquals(Object[], Object[]) , equals(Object, Object)

    method:hashCode(java.lang.Object) [NONE]

    hashCode

    public static  int hashCode?(Object o)
    Returns the hash code of a non-null argument and 0 for a null argument.
    Parameters:
    o - an object
    Returns:
    the hash code of a non-null argument and 0 for a null argument
    See Also:
    Object.hashCode()

    method:hash(java.lang.Object...) [NONE]

    hash

    public static  int hash?(Object... values)
    Generates 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 - the values to be hashed
    Returns:
    a hash value of the sequence of input values
    See Also:
    Arrays.hashCode(Object[]), List.hashCode()

    method:toString(java.lang.Object) [NONE]

    toString

    public static  String toString?(Object o)
    Returns the result of calling toString for a non- null argument and "null" for a null argument.
    Parameters:
    o - an object
    Returns:
    the result of calling toString for a non- null argument and "null" for a null argument
    See Also:
    Object.toString(), String.valueOf(Object)

    method:toString(java.lang.Object,java.lang.String) [NONE]

    toString

    public static  String toString?(Object o, String nullDefault)
    Returns the result of calling toString on the first argument if the first argument is not null and returns the second argument otherwise.
    Parameters:
    o - an object
    nullDefault - string to return if the first argument is null
    Returns:
    the result of calling toString on the first argument if it is not null and the second argument otherwise.
    See Also:
    toString(Object)

  • compare

    public static  <T> int compare?(T a, T b, Comparator<? super T> c)
    Returns 0 if the arguments are identical and 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.

    Type Parameters:
    T - the type of the objects being compared
    Parameters:
    a - an object
    b - an object to be compared with a
    c - the Comparator to compare the first two arguments
    Returns:
    0 if the arguments are identical and c.compare(a, b) otherwise.
    See Also:
    Comparable, Comparator

  • requireNonNull

    public static  <T> T requireNonNull?(T obj)
    Checks that the specified object reference is not null. This method is designed primarily for doing parameter validation in methods and constructors, as demonstrated below:
     public Foo(Bar bar) {
     this.bar = Objects.requireNonNull(bar);
 }
    Type Parameters:
    T - the type of the reference
    Parameters:
    obj - the object reference to check for nullity
    Returns:
    obj if not null
    Throws:
    NullPointerException - if obj is null

  • requireNonNull

    public static  <T> T requireNonNull?(T obj, String message)
    Checks that the specified object reference is not null and throws a customized NullPointerException if it is. This method is designed primarily for doing parameter validation in methods and constructors with multiple parameters, as demonstrated below:
     public Foo(Bar bar, Baz baz) {
     this.bar = Objects.requireNonNull(bar, "bar must not be null");
     this.baz = Objects.requireNonNull(baz, "baz must not be null");
 }
    Type Parameters:
    T - the type of the reference
    Parameters:
    obj - the object reference to check for nullity
    message - detail message to be used in the event that a NullPointerException is thrown
    Returns:
    obj if not null
    Throws:
    NullPointerException - if obj is null

    • method:isNull(java.lang.Object) [NONE]

    isNull

    public static  boolean isNull?(Object obj)
    Returns true if the provided reference is null otherwise returns false.
    API Note:
    This method exists to be used as a Predicate, filter(Objects::isNull)
    Parameters:
    obj - a reference to be checked against null
    Returns:
    true if the provided reference is null otherwise false
    Since:
    1.8
    See Also:
    Predicate

    method:nonNull(java.lang.Object) [NONE]

    nonNull

    public static  boolean nonNull?(Object obj)
    Returns true if the provided reference is non-null otherwise returns false.
    API Note:
    This method exists to be used as a Predicate, filter(Objects::nonNull)
    Parameters:
    obj - a reference to be checked against null
    Returns:
    true if the provided reference is non-null otherwise false
    Since:
    1.8
    See Also:
    Predicate

  • requireNonNullElse

    public static  <T> T requireNonNullElse?(T obj, T defaultObj)
    Returns the first argument if it is non-null and otherwise returns the non-null second argument.
    Type Parameters:
    T - the type of the reference
    Parameters:
    obj - an object
    defaultObj - a non-null object to return if the first argument is null
    Returns:
    the first argument if it is non-null and otherwise the second argument if it is non-null
    Throws:
    NullPointerException - if both obj is null and defaultObj is null
    Since:
    9

  • requireNonNullElseGet

    public static  <T> T requireNonNullElseGet?(T obj, Supplier<? extends T> supplier)
    Returns the first argument if it is non-null and otherwise returns the non-null value of supplier.get().
    Type Parameters:
    T - the type of the first argument and return type
    Parameters:
    obj - an object
    supplier - of a non-null object to return if the first argument is null
    Returns:
    the first argument if it is non-null and otherwise the value from supplier.get() if it is non-null
    Throws:
    NullPointerException - if both obj is null and either the supplier is null or the supplier.get() value is null
    Since:
    9

  • requireNonNull

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

    Unlike the method requireNonNull(Object, String) , this method allows creation of the message to be deferred until after the null check is made. While this may confer a performance advantage in the non-null case, when deciding to call this method care should be taken that the costs of creating the message supplier are less than the cost of just creating the string message directly.

    Type Parameters:
    T - the type of the reference
    Parameters:
    obj - the object reference to check for nullity
    messageSupplier - supplier of the detail message to be used in the event that a NullPointerException is thrown
    Returns:
    obj if not null
    Throws:
    NullPointerException - if obj is null
    Since:
    1.8
    		•

    method:checkIndex(int,int) [NONE]

    checkIndex

    public static  int checkIndex?(int index, int length)
    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 - the index
    length - the upper-bound (exclusive) of the range
    Returns:
    index if it is within bounds of the range
    Throws:
    IndexOutOfBoundsException - if the index is out of bounds
    Since:
    9

    method:checkFromToIndex(int,int,int) [NONE]

    checkFromToIndex

    public static  int checkFromToIndex?(int fromIndex, int toIndex, int length)
    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 - the lower-bound (inclusive) of the sub-range
    toIndex - the upper-bound (exclusive) of the sub-range
    length - the upper-bound (exclusive) the range
    Returns:
    fromIndex if the sub-range within bounds of the range
    Throws:
    IndexOutOfBoundsException - if the sub-range is out of bounds
    Since:
    9

    method:checkFromIndexSize(int,int,int) [NONE]

    checkFromIndexSize

    public static  int checkFromIndexSize?(int fromIndex, int size, int length)
    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 - the lower-bound (inclusive) of the sub-interval
    size - the size of the sub-range
    length - the upper-bound (exclusive) of the range
    Returns:
    fromIndex if the sub-range within bounds of the range
    Throws:
    IndexOutOfBoundsException - if the sub-range is out of bounds
    Since:
    9

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