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What does undo command do?
Undo is an interaction technique which is implemented in many computer programs. It erases the last change done to the document, reverting it to an older state. In some more advanced programs, such as graphic processing, undo will negate the last command done to the file being edited.
What is the reverse action of undo?
Undo, redo, and other shortcut key functions
| Command SHORTCUT KEY | Procedure |
|---|---|
| Undo CTRL+Z | To reverse your last action, press CTRL+Z. You can reverse more than one action. |
How do you undo an action?
To undo an action press Ctrl+Z.
Can you undo a design pattern?
The memento pattern is a software design pattern that provides the ability to restore an object to its previous state (undo via rollback). The memento pattern is implemented with three objects: the originator, a caretaker and a memento. The originator is some object that has an internal state.
Is used to reverse the effect of undo command?
To reverse your last action, press CTRL+Z. To reverse your last Undo, press CTRL+Y.
How can you use the Command pattern to implement undo and redo features?
When doing an undo, we take the top command from the undo stack and execute its undo() what restores the “original” state. The undone command is pushed to the redoStack(). When doing a redo, we take the top command from the redo stack and execute its redo() what restores the “new” state.
How do you implement undo and redo?
If “UNDO” string is encountered, pop the top element from Undo stack and push it to Redo stack. If “REDO” string is encountered, pop the top element of Redo stack and push it into the Undo stack.
How to undo, redo, or repeat an action?
Undo, redo, or repeat an action. 1 Undo an action. To undo an action press Ctrl+Z. If you prefer your mouse, click Undo on the Quick Access Toolbar. You can press Undo (or CTRL+Z 2 Redo an action. 3 Repeat an action. See More….
How does the undo and redo alert work?
When initiated in this manner, an alert asks the user to confirm or cancel the undo or redo operation. Briefly and precisely describe the operation to be undone or redone. The undo and redo alert title automatically includes a prefix of “Undo ” or “Redo ” (including the trailing space).
How to implement a simple Undo / Redo for actions in Java?
Simply wrap the object in a new class and whenever its state changes, update it. The Command pattern stores the original object (that we want to support undo/redo) and the memento object, which we need in case of an undo. Moreover, 2 methods are defined:
How to implement a simple Undo / Redo for swing?
Take a look at the Command Pattern, its uses include implementing undo/redo functionality. This tutorial explains the fundamental of the Command Pattern and the undo/redo mechanism for Swing. Hope it helps. You have to define undo (), redo () operations along with execute () in Command interface itself. Define a State in your ConcreteCommand class.