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The purpose of this Editor class is to serve as the Originator, which is responsible for creating Memento objects (EditorState) that capture the state of the editor, as well as restoring the state of the editor from a given Memento. It encapsulates the state within the content attribute and provides methods to create and restore Memento objects.
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package MementoPattern;
import java.util.ArrayList;
import java.util.List;
//This is out Caretaker
public class History {
//We could actually use a stack here - but I have chosen to use a LIST
private List<EditorState> states = new ArrayList<>();
public void push(EditorState state) {
states.add(state);
}
public EditorState pop() {
var lastIndex = states.size() - 1;
var lastState = states.get(lastIndex);
states.remove(lastState);
return lastState;
}
} |
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