A dependency filter is used to limit or extend the dependencies for a given operation. They are most of the time used by the dependency resolution task to select the dependencies that should be part of the resolution.
The interface defines a stateless strategy that shouldn't depend on external information, only on the one that is
passed to the filterBundleDependency(
This interface is also an external extension point for the dependency resolution task.
Clients should implement this interface. When doing so, make sure to adhere to the contract specified by
hashCode() and equals(
Common dependency filters can be retrieved using the static factory methods in this interface.
public static DependencyFilter | chain( Creates a chain dependency filter. |
public boolean | Checks if this filter equals to the argument. |
public BundleDependencyInformation | filterBundleDependency( Filters the dependency information. |
public int | hashCode() Returns a hash code value for the object. |
public static DependencyFilter | identity() Gets the identity dependency filter. |
public static DependencyFilter | none() Gets the none dependency filter. |
A chain dependency filter will call all filters in succession with the output of the previous filter as the input
to the next. If any of the filters return null
, the invocation chain will break, and
null
is returned.
null
.Two dependency filters equal if they produce the same results for the same inputs given the same circumstances.
Indicates whether some other object is "equal to" this one.
The equals
method implements an equivalence relation on non-null object references:
- It is reflexive: for any non-null reference value
x
,x.equals(x)
should returntrue
. - It is symmetric: for any non-null reference values
x
andy
,x.equals(y)
should returntrue
if and only ify.equals(x)
returnstrue
. - It is transitive: for any non-null reference values
x
,y
, andz
, ifx.equals(y)
returnstrue
andy.equals(z)
returnstrue
, thenx.equals(z)
should returntrue
. - It is consistent: for any non-null reference values
x
andy
, multiple invocations ofx.equals(y)
consistently returntrue
or consistently returnfalse
, provided no information used inequals
comparisons on the objects is modified. - For any non-null reference value
x
,x.equals(null)
should returnfalse
.
The equals
method for class Object
implements the most discriminating possible equivalence
relation on objects; that is, for any non-null reference values x
and y
, this method returns
true
if and only if x
and y
refer to the same object (x == y
has the value
true
).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden,
so as to maintain the general contract for the hashCode
method, which states that equal objects must have
equal hash codes.
true
if this object is the same as the obj argument; false
otherwise.The method implementation should examine the input dependency information and may perform arbitrary operations to transform the dependencies.
If the owner
argument is null
, then the dependency information is the root dependencies
that were passed as a direct input from the user.
null
, then this is the root dependency
information for the operation.null
to omit all dependencies. May also be
empty.
The general contract of hashCode
is:
- Whenever it is invoked on the same object more than once during an execution of a Java application, the
hashCode
method must consistently return the same integer, provided no information used inequals
comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. - If two objects are equal according to the
equals(Object)
method, then calling thehashCode
method on each of the two objects must produce the same integer result. - It is not required that if two objects are unequal according to the
Object.equals(
Object) method, then calling thehashCode
method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by class Object
does return distinct
integers for distinct objects. (This is typically implemented by converting the internal address of the object
into an integer, but this implementation technique is not required by the Java™ programming language.)
The identity dependency filter returns the input dependency information without modification.
The none dependency filter will omit all dependencies. It always returns BundleDependencyInformation.EMPTY.