Enum HelperInvocations
- java.lang.Object
-
- java.lang.Enum<HelperInvocations>
-
- net.sf.jguiraffe.di.impl.HelperInvocations
-
- All Implemented Interfaces:
Serializable
,Comparable<HelperInvocations>
,Invokable
public enum HelperInvocations extends Enum<HelperInvocations> implements Invokable
An enumeration class defining some simple helper
Invokable
implementations.There are cases where an
Invokable
is needed, but no concrete value object is available. For instance, when creating a bean an initializer script may be supported, but it is optional. This enumeration class provides helper objects which can be used for optional invocations rather than doing null checks all the time. So this is an application of the null object pattern.The constants defined by this class are dummy implementations which do not actually perform any meaningful action. They differ in the values returned by their implementation of the
invoke()
method. Because these implementations are state-less, they can be defined as enumeration constants and shared between all interested parties.- Since:
- 1.1
- Version:
- $Id: HelperInvocations.java 208 2012-02-11 20:57:33Z oheger $
- Author:
- Oliver Heger
-
-
Enum Constant Summary
Enum Constants Enum Constant Description IDENTITY_INVOCATION
An implementation ofInvokable
which realizes an identity invocation.NULL_INVOCATION
A specializedInvokable
implementation which always returns null in itsinvoke()
implementation.
-
Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description List<Dependency>
getParameterDependencies()
Returns the dependencies for this invocation.static HelperInvocations
valueOf(String name)
Returns the enum constant of this type with the specified name.static HelperInvocations[]
values()
Returns an array containing the constants of this enum type, in the order they are declared.
-
-
-
Enum Constant Detail
-
NULL_INVOCATION
public static final HelperInvocations NULL_INVOCATION
A specializedInvokable
implementation which always returns null in itsinvoke()
implementation.
-
IDENTITY_INVOCATION
public static final HelperInvocations IDENTITY_INVOCATION
An implementation ofInvokable
which realizes an identity invocation. It always returns the object passed in as invocation target without any further modifications.
-
-
Method Detail
-
values
public static HelperInvocations[] values()
Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:for (HelperInvocations c : HelperInvocations.values()) System.out.println(c);
- Returns:
- an array containing the constants of this enum type, in the order they are declared
-
valueOf
public static HelperInvocations valueOf(String name)
Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)- Parameters:
name
- the name of the enum constant to be returned.- Returns:
- the enum constant with the specified name
- Throws:
IllegalArgumentException
- if this enum type has no constant with the specified nameNullPointerException
- if the argument is null
-
getParameterDependencies
public List<Dependency> getParameterDependencies()
Returns the dependencies for this invocation. This implementation always returns an empty list.- Specified by:
getParameterDependencies
in interfaceInvokable
- Returns:
- the dependencies of this
Invokable
-
-