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public final class FileAttributesContentDescriptor implements ContentDescriptor, Externalizable
ContentDescriptor implementation that is based on the attributes of a file at a given location.

This content descriptor stores the last modification time and size of the file at a given location. The location is defined by the path to the file, and the root file provider.

The content descriptors are considered to be changed if any of the above attriutes change.

Use the static factory methods to create a new instance with the given attributes.

This content descriptor is designed to represent regular files. The static factory methods will return the DirectoryContentDescriptor singleton if an attributes of a directory is passed as an argument for the instantiation. This is due to the fact that directories are to be treated as basic containers for files that contain the contents.

Methods
public static ContentDescriptor
Creates a new content descriptor for the given attributes.
public static ContentDescriptor
create(PathKey pathkey, FileEntry attrs)
Creates a new content descriptor for the given attributes.
public boolean
Indicates whether some other object is "equal to" this one.
public SakerPath
Gets the file path.
public long
Gets the last modification time in milliseconds.
public RootFileProviderKey
Gets the root file provider key.
public long
Gets the size of the file.
public int
Returns a hash code value for the object.
public static boolean
Determines if the argument attributes should be considered changed defined by the rules of this class.
public boolean
Detects changes between this content descriptor and the previous one.
public void
The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays.
public String
Returns a string representation of the object.
public void
The object implements the writeExternal method to save its contents by calling the methods of DataOutput for its primitive values or calling the writeObject method of ObjectOutput for objects, strings, and arrays.
Inherited methods
From: Object
Creates a new content descriptor for the given attributes.
pathkeyThe path key of the associated file.
attrsThe attributes of the file.
A content descriptor for the given arguments.
NullPointerExceptionIf any of the arguments are null.
public static ContentDescriptor create(PathKey pathkey, FileEntry attrs) throws NullPointerException
Creates a new content descriptor for the given attributes.
pathkeyThe path key of the associated file.
attrsThe attributes of the file.
A content descriptor for the given arguments.
NullPointerExceptionIf any of the arguments are null.
public boolean equals(Object obj)
Overridden from: Object
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 return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

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.

objthe reference object with which to compare.
true if this object is the same as the obj argument; false otherwise.
Gets the file path.
The file path.
public long getLastModifiedMillis()
Gets the last modification time in milliseconds.
The last modification time.
Gets the root file provider key.
The provider key.
public long getSize()
Gets the size of the file.
The size of the file.
public int hashCode()
Overridden from: Object
Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by HashMap.

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 in equals 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 the hashCode 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 the hashCode 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.)

a hash code value for this object.
public static boolean isChanged(BasicFileAttributes current, BasicFileAttributes prev) throws NullPointerException
Determines if the argument attributes should be considered changed defined by the rules of this class.

This method will check if the argument attributes have the same size and last modification time.

If any of the arguments represent a directory, true is returned if and only if the other argument is not a directory.

currentThe current attributes.
prevThe previous attributes.
true if the attributes changed.
NullPointerExceptionIf any if the arguments are null.
public boolean isChanged(ContentDescriptor o)
Overridden from: ContentDescriptor
Detects changes between this content descriptor and the previous one.

The default implementation compares the two objects using ContentDescriptor.equals(Object).

Implementations are encouraged to check the type of the parameter using instanceof before casting them. It is further encouraged to check the content differences against interfaces instead of direct class implementations.

One can think about this function as this is the expected content of a file, and the parameter is the actual contents. If this method returns true then the file associated with this should replace the file associated with the parameter contents. This is mainly used when synchronizing files in memory to the filesystem.

oThe previous content to examine. Might be null to represent that the previous content doesn't exist.
true if the contents described by this descriptor differs from the parameter.
Overridden from: Externalizable
The object implements the readExternal method to restore its contents by calling the methods of DataInput for primitive types and readObject for objects, strings and arrays. The readExternal method must read the values in the same sequence and with the same types as were written by writeExternal.
inthe stream to read data from in order to restore the object
IOExceptionif I/O errors occur
ClassNotFoundExceptionIf the class for an object being restored cannot be found.
public String toString()
Overridden from: Object
Returns a string representation of the object. In general, the toString method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode())
 
a string representation of the object.
public void writeExternal(ObjectOutput out) throws IOException
Overridden from: Externalizable
The object implements the writeExternal method to save its contents by calling the methods of DataOutput for its primitive values or calling the writeObject method of ObjectOutput for objects, strings, and arrays.
outthe stream to write the object to
IOExceptionIncludes any I/O exceptions that may occur