org.adougou.cline
Class BaseCommand

java.lang.Object
  |
  +--org.adougou.cline.BaseCommand

All Implemented Interfaces:

Command

Direct Known Subclasses:

ExitCommand, HelpCommand, ListCommand, PrintWorkingDirectoryCommand, TimeCommand, URLCommand, WindowCommand

public abstract class BaseCommand

extends java.lang.Object

implements Command

Base class for creating named commands. The BaseCommand constructor should be called from the constructor of a derived class that is the actual command. For example:

 class ExitCommand extends BaseCommand { 
  ExitCommand() { 
    super("exit", 0, "calls the System to exit");
  }
 }
 

For a complete example of creating a command, see the RunScriptCommand.

See Also:

RunScriptCommand

Field Summary

protected java.lang.String	help_
protected java.lang.String	name_
protected int	numArgs_
protected static BasePrompt	prompt
protected CommandRegister	register_

Constructor Summary

protected

BaseCommand(java.lang.String name, int numArgs, java.lang.String help) All inheriting classes are required to call this constructor using

Method Summary

protected void	checkPermission(java.security.Permission permission) Dervied classes that require a special permission (for example, to call the VM to exit as in the ExitCommand) should call this method to check the java.security.Permission.
void	execute(java.util.Iterator iter) This method is called internally whenever a command is executed to check the arguments.
void	execute(java.lang.String args) This method enables a command to be used independently of the command prompt.
abstract void	execute(java.lang.String[] args) This method should be overloaded by each command that is defined - it will be called by the CommandRegister after the number of arguments have been checked.
java.lang.String	getHelp() Return a the help string for this command.
java.lang.String	getName()
protected BasePrompt	getPrompt()
void	set(CommandRegister cregister) This method is called by the CommandRegister whenever a new command is registered - this gives commands access to help information for other commands - eg.

Methods inherited from class java.lang.Object

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

Field Detail

name_

protected java.lang.String name_

numArgs_

protected int numArgs_

register_

protected CommandRegister register_

help_

protected java.lang.String help_

prompt

protected static BasePrompt prompt

Constructor Detail

BaseCommand

protected BaseCommand(java.lang.String name,
                      int numArgs,
                      java.lang.String help)

All inheriting classes are required to call this constructor using

super(name, numArgs, help)

.

Parameters:

name - the name of the command - an exception will be thrown if a command already exists with this name

numArgs - the number of arguments this command takes. -1 can be specified if the command takes a variable number of arguments, in which case it is up to the derived command to carefully check the arguments.

help - this string is returned to the user when they request help about a command. It should include a brief description of what the command accomplishes and what each of the required arguments is.

Method Detail

set

public void set(CommandRegister cregister)

This method is called by the CommandRegister whenever a new command is registered - this gives commands access to help information for other commands - eg. see the HelpCommand.

Specified by:

set in interface Command

checkPermission

protected void checkPermission(java.security.Permission permission)

Dervied classes that require a special permission (for example, to call the VM to exit as in the ExitCommand) should call this method to check the java.security.Permission. If permission is not granted, this permission will be added to a list of failed permissions for this command, the command will be disabled, and a message describing the permission failure will be displayed to the user if they attempt to execute the command.

getPrompt

protected BasePrompt getPrompt()

getName

public java.lang.String getName()

Specified by:

getName in interface Command

execute

public void execute(java.lang.String args)

This method enables a command to be used independently of the command prompt. You instantiate a command, and then execute it by passing a string containing the arguments. If the arguments are not properly formatted, an error will be printed.

execute

public abstract void execute(java.lang.String[] args)

This method should be overloaded by each command that is defined - it will be called by the CommandRegister after the number of arguments have been checked.

Specified by:

execute in interface Command

execute

public void execute(java.util.Iterator iter)

This method is called internally whenever a command is executed to check the arguments. After checking arguments, it will call the execute(String[]) method for the specific command.

Specified by:

execute in interface Command

getHelp

public java.lang.String getHelp()

Return a the help string for this command. This is basically the help string required in the constructor for all BaseCommands.

Specified by:

getHelp in interface Command