public class

ImmutableDescriptor

extends Object
implements Descriptor
java.lang.Object
   ↳ javax.management.ImmutableDescriptor

Class Overview

An immutable descriptor.

Summary

Fields
public static final ImmutableDescriptor EMPTY_DESCRIPTOR An empty descriptor.
Public Constructors
ImmutableDescriptor(String[] fieldNames, Object[] fieldValues)
Construct a descriptor containing the given fields and values.
ImmutableDescriptor(String... fields)
Construct a descriptor containing the given fields.
ImmutableDescriptor(Map<String, ?> fields)

Construct a descriptor where the names and values of the fields are the keys and values of the given Map.

Public Methods
Descriptor clone()

Returns a descriptor which is equal to this descriptor.

boolean equals(Object o)
Compares this descriptor to the given object.
final String[] getFieldNames()
Returns all the field names in the descriptor.
final Object getFieldValue(String fieldName)
Returns the value for a specific field name, or null if no value is present for that name.
final Object[] getFieldValues(String... fieldNames)
Returns all the field values in the descriptor as an array of Objects.
final String[] getFields()
Returns all of the fields contained in this descriptor as a string array.
int hashCode()

Returns the hash code value for this descriptor.

boolean isValid()
Returns true if all of the fields have legal values given their names.
final void removeField(String fieldName)
Removes a field from the descriptor.
final void setField(String fieldName, Object fieldValue)
This operation is unsupported since this class is immutable.
final void setFields(String[] fieldNames, Object[] fieldValues)
This operation is unsupported since this class is immutable.
String toString()
Returns a string representation of the object.
static ImmutableDescriptor union(Descriptor... descriptors)

Return an ImmutableDescriptor whose contents are the union of the given descriptors.

[Expand]
Inherited Methods
From class java.lang.Object
From interface javax.management.Descriptor

Fields

public static final ImmutableDescriptor EMPTY_DESCRIPTOR

An empty descriptor.

Public Constructors

public ImmutableDescriptor (String[] fieldNames, Object[] fieldValues)

Construct a descriptor containing the given fields and values.

Throws
IllegalArgumentException if either array is null, or if the arrays have different sizes, or if a field name is null or empty, or if the same field name appears more than once.

public ImmutableDescriptor (String... fields)

Construct a descriptor containing the given fields. Each String must be of the form fieldName=fieldValue. The field name ends at the first = character; for example if the String is a=b=c then the field name is a and its value is b=c.

Throws
IllegalArgumentException if the parameter is null, or if a field name is empty, or if the same field name appears more than once, or if one of the strings does not contain an = character.

public ImmutableDescriptor (Map<String, ?> fields)

Construct a descriptor where the names and values of the fields are the keys and values of the given Map.

Throws
IllegalArgumentException if the parameter is null, or if a field name is null or empty, or if the same field name appears more than once (which can happen because field names are not case sensitive).

Public Methods

public Descriptor clone ()

Returns a descriptor which is equal to this descriptor. Changes to the returned descriptor will have no effect on this descriptor, and vice versa.

This method returns the object on which it is called. A subclass can override it to return another object provided the contract is respected.

Returns
  • a clone of this instance.
Throws
RuntimeOperationsException for illegal value for field Names or field Values. If the descriptor construction fails for any reason, this exception will be thrown.

public boolean equals (Object o)

Compares this descriptor to the given object. The objects are equal if the given object is also a Descriptor, and if the two Descriptors have the same field names (possibly differing in case) and the same associated values. The respective values for a field in the two Descriptors are equal if the following conditions hold:

  • If one value is null then the other must be too.
  • If one value is a primitive array then the other must be a primitive array of the same type with the same elements.
  • If one value is an object array then the other must be too and deepEquals(Object[], Object[]) must return true.
  • Otherwise equals(Object) must return true.

Parameters
o the object to compare with.
Returns
  • true if the objects are the same; false otherwise.

public final String[] getFieldNames ()

Returns all the field names in the descriptor.

Returns
  • String array of field names. If the descriptor is empty, you will get an empty array.

public final Object getFieldValue (String fieldName)

Returns the value for a specific field name, or null if no value is present for that name.

Parameters
fieldName the field name.
Returns
  • the corresponding value, or null if the field is not present.

public final Object[] getFieldValues (String... fieldNames)

Returns all the field values in the descriptor as an array of Objects. The returned values are in the same order as the fieldNames String array parameter.

Parameters
fieldNames String array of the names of the fields that the values should be returned for. If the array is empty then an empty array will be returned. If the array is null then all values will be returned, as if the parameter were the array returned by getFieldNames(). If a field name in the array does not exist, including the case where it is null or the empty string, then null is returned for the matching array element being returned.
Returns
  • Object array of field values. If the list of fieldNames is empty, you will get an empty array.

public final String[] getFields ()

Returns all of the fields contained in this descriptor as a string array.

Returns
  • String array of fields in the format fieldName=fieldValue
    If the value of a field is not a String, then the toString() method will be called on it and the returned value, enclosed in parentheses, used as the value for the field in the returned array. If the value of a field is null, then the value of the field in the returned array will be empty. If the descriptor is empty, you will get an empty array.

public int hashCode ()

Returns the hash code value for this descriptor. The hash code is computed as the sum of the hash codes for each field in the descriptor. The hash code of a field with name n and value v is n.toLowerCase().hashCode() ^ h. Here h is the hash code of v, computed as follows:

  • If v is null then h is 0.
  • If v is a primitive array then h is computed using the appropriate overloading of java.util.Arrays.hashCode.
  • If v is an object array then h is computed using deepHashCode(Object[]).
  • Otherwise h is v.hashCode().

Returns
  • A hash code value for this object.

public boolean isValid ()

Returns true if all of the fields have legal values given their names. This method always returns true, but a subclass can override it to return false when appropriate.

Returns
  • true if the values are legal.
Throws
RuntimeOperationsException if the validity checking fails. The method returns false if the descriptor is not valid, but throws this exception if the attempt to determine validity fails.

public final void removeField (String fieldName)

Removes a field from the descriptor.

Parameters
fieldName String name of the field to be removed. If the field name is illegal or the field is not found, no exception is thrown.
Throws
RuntimeOperationsException if a field of the given name exists and the descriptor is immutable. The wrapped exception will be an UnsupportedOperationException.

public final void setField (String fieldName, Object fieldValue)

This operation is unsupported since this class is immutable. If this call would change a mutable descriptor with the same contents, then a RuntimeOperationsException wrapping an UnsupportedOperationException is thrown. Otherwise, the behavior is the same as it would be for a mutable descriptor: either an exception is thrown because of illegal parameters, or there is no effect.

Parameters
fieldName The field name to be set. Cannot be null or empty.
fieldValue The field value to be set for the field name. Can be null if that is a valid value for the field.
Throws
RuntimeOperationsException

public final void setFields (String[] fieldNames, Object[] fieldValues)

This operation is unsupported since this class is immutable. If this call would change a mutable descriptor with the same contents, then a RuntimeOperationsException wrapping an UnsupportedOperationException is thrown. Otherwise, the behavior is the same as it would be for a mutable descriptor: either an exception is thrown because of illegal parameters, or there is no effect.

Parameters
fieldNames String array of field names. The array and array elements cannot be null.
fieldValues Object array of the corresponding field values. The array cannot be null. Elements of the array can be null.
Throws
RuntimeOperationsException

public String toString ()

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())

Returns
  • a string representation of the object.

public static ImmutableDescriptor union (Descriptor... descriptors)

Return an ImmutableDescriptor whose contents are the union of the given descriptors. Every field name that appears in any of the descriptors will appear in the result with the value that it has when the method is called. Subsequent changes to any of the descriptors do not affect the ImmutableDescriptor returned here.

In the simplest case, there is only one descriptor and the returned ImmutableDescriptor is a copy of its fields at the time this method is called:

 Descriptor d = something();
 ImmutableDescriptor copy = ImmutableDescriptor.union(d);

Parameters
descriptors the descriptors to be combined. Any of the descriptors can be null, in which case it is skipped.
Returns
  • an ImmutableDescriptor that is the union of the given descriptors. The returned object may be identical to one of the input descriptors if it is an ImmutableDescriptor that contains all of the required fields.
Throws
IllegalArgumentException if two Descriptors contain the same field name with different associated values. Primitive array values are considered the same if they are of the same type with the same elements. Object array values are considered the same if deepEquals(Object[], Object[]) returns true.