jmri
Interface MemoryManager

All Superinterfaces:

Manager

All Known Implementing Classes:

AbstractMemoryManager, DefaultMemoryManager

public interface MemoryManager
extends Manager

Locate a Memory object representing some specific information.

Memory objects are obtained from a MemoryManager, which in turn is generally located from the InstanceManager. A typical call sequence might be:

 Memory memory = InstanceManager.memoryManagerInstance().provideMemory("status");

Each Memory has a two names. The "user" name is entirely free form, and can be used for any purpose. The "system" name is provided by the system-specific implementations, if any, and provides a unique mapping to the layout control system (e.g. LocoNet, NCE, etc) and address within that system. Note that most (all?) layout systems don't have anything corresponding to this, in which case the "Internal" Memory objects are still available with names like IM23.

Much of the book-keeping is implemented in the AbstractMemoryManager class, which can form the basis for a system-specific implementation.

This file is part of JMRI.

JMRI is free software; you can redistribute it and/or modify it under the terms of version 2 of the GNU General Public License as published by the Free Software Foundation. See the "COPYING" file for a copy of this license.

JMRI is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Author:

Bob Jacobsen Copyright (C) 2004

See Also:

Memory, AbstractMemoryManager, InstanceManager

Method Summary

Memory	getBySystemName(String systemName) Locate an instance based on a system name.
Memory	getByUserName(String userName) Locate an instance based on a user name.
Memory	getMemory(String name) Locate via user name, then system name if needed.
List	getSystemNameList() Get a list of all Memory objects' system names.
Memory	newMemory(String systemName, String userName) Return an instance with the specified system and user names.
Memory	provideMemory(String name) Locate via user name, then system name if needed.

Methods inherited from interface jmri.Manager

addPropertyChangeListener, deregister, dispose, makeSystemName, register, removePropertyChangeListener, systemLetter, typeLetter

Method Detail

provideMemory

Memory provideMemory(String name)

Locate via user name, then system name if needed. If that fails, create a new Memory. If the name is a valid system name, it will be used for the new Memory. Otherwise, the makeSystemName method will attempt to turn it into a valid system name.

Parameters:

name -

Returns:

Never null under normal circumstances

getMemory

Memory getMemory(String name)

Locate via user name, then system name if needed. If that fails, return null

Parameters:

name -

Returns:

null if no match found

getBySystemName

Memory getBySystemName(String systemName)

Locate an instance based on a system name. Returns null if no instance already exists.

Returns:

requested Memory object or null if none exists

getByUserName

Memory getByUserName(String userName)

Locate an instance based on a user name. Returns null if no instance already exists.

Returns:

requested Memory object or null if none exists

newMemory

Memory newMemory(String systemName,
                 String userName)

Return an instance with the specified system and user names. Note that two calls with the same arguments will get the same instance; there is only one Memory object representing a given physical Memory and therefore only one with a specific system or user name.

This will always return a valid object reference; a new object will be created if necessary. In that case:

• If a null reference is given for user name, no user name will be associated with the Memory object created; a valid system name must be provided
• If both names are provided, the system name defines the hardware access of the desired Memory, and the user address is associated with it. The system name must be valid.

Note that it is possible to make an inconsistent request if both addresses are provided, but the given values are associated with different objects. This is a problem, and we don't have a good solution except to issue warnings. This will mostly happen if you're creating Memory objects when you should be looking them up.

Returns:

requested Memory object (never null)

getSystemNameList

List getSystemNameList()

Get a list of all Memory objects' system names.

Specified by:

getSystemNameList in interface Manager