java.lang.Object | |
↳ | com.facebook.common.internal.Objects |
Helper functions that can operate on any Object
.
See the Guava User Guide on writing
Object
methods with Objects
.
Nested Classes | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
class | Objects.ToStringHelper | Support class for toStringHelper(Class>) . |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
static boolean |
equal(Object a, Object b)
Determines whether two possibly-null objects are equal.
| ||||||||||
static <T> T |
firstNonNull(T first, T second)
Returns the first of two given parameters that is not
null , if
either is, or otherwise throws a NullPointerException. | ||||||||||
static int |
hashCode(Object... objects)
Generates a hash code for multiple values.
| ||||||||||
static Objects.ToStringHelper |
toStringHelper(String className)
Creates an instance of
Objects.ToStringHelper in the same manner as
toStringHelper(Object) , but using className instead
of using an instance's getClass() . | ||||||||||
static Objects.ToStringHelper |
toStringHelper(Object self)
Creates an instance of
Objects.ToStringHelper . | ||||||||||
static Objects.ToStringHelper |
toStringHelper(Class<?> clazz)
Creates an instance of
Objects.ToStringHelper in the same manner as
toStringHelper(Object) , but using the name of clazz
instead of using an instance's getClass() . |
[Expand]
Inherited Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
![]() |
Determines whether two possibly-null objects are equal. Returns:
true
if a
and b
are both null.
true
if a
and b
are both non-null and they are
equal according to equals(Object)
.
false
in all other situations.
This assumes that any non-null objects passed to this function conform
to the equals()
contract.
Returns the first of two given parameters that is not null
, if
either is, or otherwise throws a NullPointerException.
Note: if first
is represented as an Optional,
this can be accomplished with
Optional#or(Object) first.or(second).
That approach also allows for lazy evaluation of the fallback instance,
using Optional#or(Supplier) first.or(Supplier).
first
if first
is not null
, or
second
if first
is null
and second
is
not null
NullPointerException | if both first and second were
null |
---|
Generates a hash code for multiple values. The hash code is generated by
calling hashCode(Object[])
. Note that array arguments to
this method, with the exception of a single Object array, do not get any
special handling; their hash codes are based on identity and not contents.
This is useful for implementing hashCode()
. For example,
in an object that has three properties, x
, y
, and
z
, one could write:
public int hashCode() {
return Objects.hashCode(getX(), getY(), getZ());
}
Warning: When a single object is supplied, the returned hash code does not equal the hash code of that object.
Creates an instance of Objects.ToStringHelper
in the same manner as
toStringHelper(Object)
, but using className
instead
of using an instance's getClass()
.
className | the name of the instance type |
---|
Creates an instance of Objects.ToStringHelper
.
This is helpful for implementing toString()
.
Specification by example:
// Returns "ClassName{
"
Objects.toStringHelper(this)
.toString();
// Returns "ClassName{x=1}"
Objects.toStringHelper(this)
.add("x", 1)
.toString();
// Returns "MyObject{x=1}"
Objects.toStringHelper("MyObject")
.add("x", 1)
.toString();
// Returns "ClassName{x=1, y=foo}"
Objects.toStringHelper(this)
.add("x", 1)
.add("y", "foo")
.toString();
// Returns "ClassName{x=1}"
Objects.toStringHelper(this)
.omitNullValues()
.add("x", 1)
.add("y", null)
.toString();
}}
Note that in GWT, class names are often obfuscated.
self | the object to generate the string for (typically this ),
used only for its class name |
---|
Creates an instance of Objects.ToStringHelper
in the same manner as
toStringHelper(Object)
, but using the name of clazz
instead of using an instance's getClass()
.
Note that in GWT, class names are often obfuscated.
clazz | the Class of the instance |
---|