This interface is mostly used to query children and synchronize children of directories.
It is strongly recommended that implementations of this interface are RMI-transferrable to avoid unnecessary network traffic when designing tasks for remote execution.
It is recommended that implementations adhere to the equals(
public static DirectoryVisitPredicate | Gets a directory visitor that visits only the child directories, not recursively. |
public static DirectoryVisitPredicate | Gets a directory visitor that visits only the child files, not recursively. |
public static DirectoryVisitPredicate | children() Gets a directory visitor that visits only the children of the directory. |
public default DirectoryVisitPredicate | directoryVisitor( Creates a directory visitor for the subdirectory with the given name. |
public boolean | Checks if this directory visitor would visit the same files as the parameter given the same circumstances. |
public static DirectoryVisitPredicate | Gets a directory visitor that visits every file and directory in the directory tree, recursively. |
public default NavigableSet< | Gets a set of file names which should remain untouched during synchronization. |
public int | hashCode() Returns a hash code value for the object. |
public static DirectoryVisitPredicate | nothing() Gets a directory visitor that visits none of the files. |
public static DirectoryVisitPredicate | Gets a visitor that visits all directories in the directory tree, recursively. |
public static DirectoryVisitPredicate | subFiles() Gets a directory visitor that visits all files in the directory tree, recursively. |
public static DirectoryVisitPredicate | Gets a directory visitor that synchronizes none of the files. |
public boolean | visitDirectory( Determines if the directory with the given name should be visited by the consumer. |
public boolean | Determines if the file with the given name should be visited by the consumer. |
The consumer is instructed to visit the children of the directory.
For synchronization, returning non-null
will cause the synchronizer to attempt synchronization of
the children of the parameter. If this method returns null
, the directory can be still synchronized
(but not its children, only creating the folder on the file system) by returning true
from
visitDirectory(
For file collection, returning non-null
will cause the children of the parameter directory to be
visited.
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.During the synchronization process of a directory, the files on the file system which are not present in the in-memory representation will be deleted. In other words: Any file that is present in the target directory, but not in the key-set of SakerDirectory.getChildren() will be deleted as a first step of directory synchronization. Returning a file name in this result set will cause that file to be not deleted.
The method can return null
, to signal that this deletion should not take place. This can be useful
when the user wants to ensure that no unknown files are deleted without knowing their names.
The result of this method does not affect the files which will be synchronized, but only this first stage deletion.
The default implementation returns an empty set, meaning that all files which are not contained on the in-memory hierarchy will be deleted.
null
to skip deletion.
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.)
This differs from nothing() in that it returns null
from
getSynchronizeFilesToKeep(). It can be useful if you want to synchronize a directory but only perform
the directory creation and no other operations.
For synchronization, returning true
this means that the directory should be synchronized:
If directoryVisitor(null
, then only the directory will be
created at the path.
If directoryVisitor(null
, then the synchronization of
the subdirectory with its children will proceed without calling this method.
For file collection, returning true
will cause the parameter to be part of the result set.
true
if the directory should be visited.For synchronization, this means that the file will be synchronized.
For file collection, this means that the file will be part of the result set.
true
if the file should be visited.