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SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD |
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FlexDoc/Javadoc 2.0 Demo Java Doc |
Class Objects
java.util.Objects
public final class 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.
Since:
1.7
Method Summary |
static 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).
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static 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).
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static int |
Checks if the sub-range from fromIndex (inclusive) to
toIndex (exclusive) is within the bounds of range from 0
(inclusive) to length (exclusive).
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static long |
Checks if the sub-range from fromIndex (inclusive) to
toIndex (exclusive) is within the bounds of range from 0
(inclusive) to length (exclusive).
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static int |
Checks if the index is within the bounds of the range from
0 (inclusive) to length (exclusive).
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static long |
Checks if the index is within the bounds of the range from
0 (inclusive) to length (exclusive).
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Returns 0 if the arguments are identical and
c.compare(a, b) otherwise.
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static boolean |
Returns true if the arguments are deeply equal to each other
and false otherwise.
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static boolean |
Returns true if the arguments are equal to each other
and false otherwise.
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static int |
Generates a hash code for a sequence of input values.
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static int |
Returns the hash code of a non-null argument and 0 for
a null argument.
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static boolean |
Returns true if the provided reference is null otherwise
returns false.
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static boolean |
Returns true if the provided reference is non-null
otherwise returns false.
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Checks that the specified object reference is not null.
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Checks that the specified object reference is not null and
throws a customized NullPointerException if it is.
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Checks that the specified object reference is not null and
throws a customized NullPointerException if it is.
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Returns the first argument if it is non-null and
otherwise returns the non-null second argument.
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Returns the first argument if it is non-null and otherwise
returns the non-null value of supplier.get().
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Returns the result of calling toString for a non-
null argument and "null" for a null argument.
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Returns the result of calling toString on the first
argument if the first argument is not null and returns
the second argument otherwise.
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Methods inherited from class java.lang. Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
public static boolean equals |
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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:
public static boolean deepEquals |
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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:
public static int hashCode |
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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:
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:
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:
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:
public static < T> int compare |
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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:
public static < T> T requireNonNull |
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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:
public static < T> T requireNonNull |
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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:
public static boolean isNull |
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Returns
true if the provided reference is
null otherwise
returns
false.
Parameters:
obj - a reference to be checked against null
Returns:
true if the provided reference is null otherwise
false
Since:
1.8
See Also:
public static boolean nonNull |
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Returns
true if the provided reference is non-
null
otherwise returns
false.
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:
public static < T> T requireNonNullElse |
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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:
Since:
9
public static < T> T requireNonNullElseGet |
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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
public static < T> T requireNonNull |
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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:
Since:
1.8
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:
Since:
9
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:
Since:
9
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:
Since:
9
public static long checkIndex |
(long index, long 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:
Since:
16
public static long checkFromToIndex |
(long fromIndex, long toIndex, long 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:
Since:
16
public static long checkFromIndexSize |
(long fromIndex, long size, long 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:
Since:
16
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SUMMARY: NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD |
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FlexDoc/Javadoc 2.0 Demo Java Doc |
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