Module hw06

Package provided.utils.loader.impl

Class ObjectLoaderPath<ReturnT>

java.lang.Object

provided.utils.loader.impl.ObjectLoaderPath<ReturnT>

Type Parameters:

ReturnT - The type of object loaded by this IObjectLoader

All Implemented Interfaces:

IObjectLoader<ReturnT>

public class ObjectLoaderPath<ReturnT>
extends Object
implements IObjectLoader<ReturnT>

An IObjectLoader implementation that will walk through multiple locations, defined by multiple classname prefixes, to load an object of the specified type.

Author:

swong

Field Summary

Fields

Modifier and Type	Field	Description
private ArrayList<String>	classnamePrefixes	List of of the given classname prefixes, which is effectively a path list
(package private) Function<Object[],ReturnT>	errorFac	The error factory to use in case the class is never found
private ILogger	logger	Logger to use

Constructor Summary

Constructors

Constructor	Description
ObjectLoaderPath(Function<Object[],ReturnT> errorFac, String... classnamePrefixes)	Constructor for the class.

Method Summary

Modifier and Type	Method	Description
(package private) ReturnT	exceptionHandler(Exception ex, String fullClassName, Object... params)	Handler for exceptions or running out of places to search.
ReturnT	loadInstance(String className, Object... args)	Instantiates and then delegates to a recursive IObjectLoader instance that goes through the saved list of classname prefixes searching for the partial name, className.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

logger

private ILogger logger

Logger to use

classnamePrefixes

private ArrayList<String> classnamePrefixes

List of of the given classname prefixes, which is effectively a path list

errorFac

Function<Object[],ReturnT> errorFac

The error factory to use in case the class is never found

Constructor Details

ObjectLoaderPath

public ObjectLoaderPath(Function<Object[],ReturnT> errorFac,
 String... classnamePrefixes)

Constructor for the class. The given errorFac is used to generate instances when the loadInstance() method is otherwise unable to do so because of a processing error.

Parameters:

errorFac - A factory method that takes the same array of input parameters that loadInstance() takes and returns an instance of ReturnT.

classnamePrefixes - Vararg of the prefixes to search for the given classnames. The prefixes should complete the fully qualified pathname when pre=pended to the className given to loadInstance(). The prefixes are searched in the order given.

Method Details

exceptionHandler

ReturnT exceptionHandler(Exception ex,
 String fullClassName,
 Object... params)

Handler for exceptions or running out of places to search.

Parameters:

ex - The Exception to be handled

fullClassName - The fully qualified class name being searched for

params - Intended class constructor parameters

Returns:

The error object generated by the stored errorFac.

loadInstance

public ReturnT loadInstance(String className,
 Object... args)

Instantiates and then delegates to a recursive IObjectLoader instance that goes through the saved list of classname prefixes searching for the partial name, className. If the class is never found, the exception printed and the saved errorFac will be invoked to generate an error object result.

Specified by:

loadInstance in interface IObjectLoader<ReturnT>

Parameters:

className - The fully-qualified name of the desired class which must be assignable to the ReturnT type.

args - a varargs of input parameter values for the constructor of className

Returns:

An instance of the desired class, as ReturnT