@GwtCompatible public final class Objects extends Object
Object
.
See the Guava User Guide on writing
Object
methods with Objects
.
Modifier and Type | Class and Description |
---|---|
static class |
Objects.ToStringHelper
Deprecated.
Use
MoreObjects.ToStringHelper instead. This class is
scheduled for removal in June 2016. |
Modifier and Type | Method and Description |
---|---|
static boolean |
equal(Object a,
Object b)
Determines whether two possibly-null objects are equal.
|
static <T> T |
firstNonNull(T first,
T second)
Deprecated.
Use
MoreObjects.firstNonNull(T, T) instead. This method is
scheduled for removal in June 2016. |
static int |
hashCode(Object... objects)
Generates a hash code for multiple values.
|
static Objects.ToStringHelper |
toStringHelper(Class<?> clazz)
Deprecated.
Use
MoreObjects.toStringHelper(Class) instead. This
method is scheduled for removal in June 2016. |
static Objects.ToStringHelper |
toStringHelper(Object self)
Deprecated.
Use
MoreObjects.toStringHelper(Object) instead. This
method is scheduled for removal in June 2016. |
static Objects.ToStringHelper |
toStringHelper(String className)
Deprecated.
Use
MoreObjects.toStringHelper(String) instead. This
method is scheduled for removal in June 2016. |
@CheckReturnValue public static boolean equal(@Nullable Object a, @Nullable Object b)
true
if a
and b
are both null.
true
if a
and b
are both non-null and they are
equal according to Object.equals(Object)
.
false
in all other situations.
This assumes that any non-null objects passed to this function conform
to the equals()
contract.
Note for Java 7 and later: This method should be treated as
deprecated; use Objects.equals(java.lang.Object, java.lang.Object)
instead.
@CheckReturnValue public static int hashCode(@Nullable Object... objects)
Arrays.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 Object.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.
Note for Java 7 and later: This method should be treated as
deprecated; use Objects.hash(java.lang.Object...)
instead.
@CheckReturnValue @Deprecated public static Objects.ToStringHelper toStringHelper(Object self)
MoreObjects.toStringHelper(Object)
instead. This
method is scheduled for removal in June 2016.Objects.ToStringHelper
.
This is helpful for implementing Object.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@CheckReturnValue @Deprecated public static Objects.ToStringHelper toStringHelper(Class<?> clazz)
MoreObjects.toStringHelper(Class)
instead. This
method is scheduled for removal in June 2016.Objects.ToStringHelper
in the same manner as
toStringHelper(Object)
, but using the name of clazz
instead of using an instance's Object.getClass()
.
Note that in GWT, class names are often obfuscated.
clazz
- the Class
of the instance@CheckReturnValue @Deprecated public static Objects.ToStringHelper toStringHelper(String className)
MoreObjects.toStringHelper(String)
instead. This
method is scheduled for removal in June 2016.Objects.ToStringHelper
in the same manner as
toStringHelper(Object)
, but using className
instead
of using an instance's Object.getClass()
.className
- the name of the instance type@CheckReturnValue @Deprecated public static <T> T firstNonNull(@Nullable T first, @Nullable T second)
MoreObjects.firstNonNull(T, T)
instead. This method is
scheduled for removal in June 2016.null
, if
either is, or otherwise throws a NullPointerException
.
Note: if first
is represented as an Optional
,
this can be accomplished with
first.or(second).
That approach also allows for lazy evaluation of the fallback instance,
using 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
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