myhw3.command

Interface CommandHistory

All Known Implementing Classes:

CommandHistoryObj

public interface CommandHistory

An unbounded list of commands with undo/redo capability.

Logically, the functionality is described in terms of two stacks: undoable and redoable, both initially empty.

Method Summary

Modifier and Type	Method and Description
void	add(Command cmd) Add command undoable and clear redoable.
boolean	redo() Pop command from redoable, redo it, then push it onto undoable.
boolean	undo() Pop command from undoable, undo it, then push it onto redoable.

Method Detail

add

void add(Command cmd)

Add command undoable and clear redoable.

Parameters:

cmd - the command to be run.

undo

boolean undo()

Pop command from undoable, undo it, then push it onto redoable.

redo

boolean redo()

Pop command from redoable, redo it, then push it onto undoable.