Command pattern assignment

assignments/command_pattern/Command.java

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+package assignments.command_pattern;
+
+public interface Command {
+    void execute();
+
+    void undo();
+
+    void redo();
+}

assignments/command_pattern/CopyCommand.java

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+package assignments.command_pattern;
+
+public class CopyCommand implements Command {
+    private Text text;
+    private int start;
+    private int end;
+
+    public CopyCommand(Text text, int start, int end) {
+        this.text = text;
+        this.start = start;
+        this.end = end;
+    }
+
+    @Override
+    public void execute() {
+        text.copy(start, end);
+    }
+
+    @Override
+    public void undo() {
+        // copying normally does not require an undo function
+    }
+
+    @Override
+    public void redo() {
+        // copying normally does not require an redo function
+    }
+}

assignments/command_pattern/CutCommand.java

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+package assignments.command_pattern;
+
+public class CutCommand implements Command {
+    private Text text;
+    private String removedText;
+    private int start;
+    private int end;
+
+    public CutCommand(Text text, int start, int end) {
+        this.text = text;
+        this.start = start;
+        this.end = end;
+    }
+
+    @Override
+    public void execute() {
+        removedText = text.cut(start, end);
+    }
+
+    @Override
+    public void undo() {
+        text.insert(start, removedText);
+    }
+
+    @Override
+    public void redo() {
+        execute();
+    }
+}

assignments/command_pattern/Keyboard.java

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+package assignments.command_pattern;
+
+import java.util.Map;
+import java.util.HashMap;
+
+public class Keyboard {
+    private Map<String, Command> keyBindings = new HashMap<>();
+    private Command lastCommand = new NoCommand();
+    private Command redoCommand = new NoCommand();
+
+    public void setCommand(String key, Command command) {
+        keyBindings.put(key, command);
+    }
+
+    public void pressKey(String key) {
+        Command command = keyBindings.getOrDefault(key, new NoCommand());
+        command.execute();
+        lastCommand = command;
+        redoCommand = new NoCommand();
+    }
+
+    public void undoKey() {
+        lastCommand.undo();
+        redoCommand = lastCommand;
+        lastCommand = new NoCommand();
+    }
+
+    public void redoKey() {
+        redoCommand.redo();
+        lastCommand = redoCommand;
+        redoCommand = new NoCommand();
+    }
+}

assignments/command_pattern/NoCommand.java

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+package assignments.command_pattern;
+
+public class NoCommand implements Command {
+    public NoCommand() {
+    }
+
+    @Override
+    public void execute() {
+    }
+
+    @Override
+    public void undo() {
+    }
+
+    @Override
+    public void redo() {
+    }
+}

assignments/command_pattern/PasteCommand.java

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+package assignments.command_pattern;
+
+public class PasteCommand implements Command {
+    private Text text;
+    private String clipBoard;
+    private int start;
+
+    public PasteCommand(Text text, int start) {
+        this.text = text;
+        this.start = start;
+    }
+
+    @Override
+    public void execute() {
+        clipBoard = text.getClipBoard();
+        text.insert(start, clipBoard);
+    }
+
+    @Override
+    public void undo() {
+        text.delete(start, start + clipBoard.length());
+    }
+
+    @Override
+    public void redo() {
+        text.insert(start, clipBoard);
+    }
+}

assignments/command_pattern/Text.java

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+package assignments.command_pattern;
+
+public class Text {
+    private StringBuilder textBlock = new StringBuilder();
+    private String clipBoard = "";
+
+    public Text(String initialTextBlock) {
+        this.textBlock.append(initialTextBlock);
+    }
+
+    public String getClipBoard() {
+        return clipBoard;
+    }
+
+    public void setClipBoard(String text) {
+        this.clipBoard = text;
+    }
+
+    public String getTextBlock() {
+        return textBlock.toString();
+    }
+
+    public String copy(int start, int end) {
+        clipBoard = textBlock.substring(start, end);
+        return clipBoard;
+    }
+
+    public String cut(int start, int end) {
+        clipBoard = textBlock.substring(start, end);
+        textBlock.delete(start, end);
+        return clipBoard;
+    }
+
+    public void insert(int start, String word) {
+        textBlock.insert(start, word);
+    }
+
+    public void delete(int start, int end) {
+        textBlock.delete(start, end);
+    }
+}

assignments/command_pattern/TextEditor.java

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+package assignments.command_pattern;
+
+import java.util.Scanner;
+
+public class TextEditor {
+    public static void main(String[] args) {
+
+        // Setting up the StringBuffer element
+        StringBuffer currentBuffer = new StringBuffer("Hello! Welcome to my text editor program! \n");
+        currentBuffer.append("We are going to learn about copying, cutting, and pasting. \n");
+        currentBuffer.append("Are you ready to get started? \n");
+        currentBuffer.append("We will only be interacting with the first instance of any text! \n");
+        currentBuffer.append("Let's practice on this greeting!");
+
+        // Create the Text, Keyboard, clipboard, and start index elements
+        String currentText = currentBuffer.toString();
+        Text text = new Text(currentText);
+        Keyboard keyboard = new Keyboard();
+        int start = 0;
+        int end = 0;
+        int paste = 0;
+
+        // Get ready to handle user input
+        Scanner inputScanner = new Scanner(System.in);
+        String userInput;
+
+        // Display Greeting
+        System.out.println(currentText);
+
+        // Copy setup
+        System.out.println("\nPick a word in the greeting to copy!");
+        userInput = inputScanner.nextLine();
+
+        if (currentText.contains(userInput)) {
+            start = text.getTextBlock().indexOf(userInput);
+            end = start + userInput.length();
+            keyboard.setCommand("copy", new CopyCommand(text, start, end));
+            keyboard.pressKey("copy");
+        } else {
+            System.out.println("Could not find: " + userInput);
+        }
+
+        // Cut setup
+        System.out.println("\nPick a word in the greeting to cut!");
+        userInput = inputScanner.nextLine();
+
+        if (currentText.contains(userInput)) {
+            start = text.getTextBlock().indexOf(userInput);
+            end = start + userInput.length();
+            keyboard.setCommand("cut", new CutCommand(text, start, end));
+            keyboard.pressKey("cut");
+        } else {
+            System.out.println("Could not find: " + userInput);
+        }
+
+        // Paste setup
+        System.out.println("\nShould we paste our clipboard?");
+        userInput = inputScanner.nextLine();
+
+        if (userInput.equalsIgnoreCase("yes") || userInput.equalsIgnoreCase("y")) {
+            System.out.println("\nWhat index would you like to paste to?");
+            paste = inputScanner.nextInt();
+            inputScanner.nextLine();
+            keyboard.setCommand("paste", new PasteCommand(text, paste));
+            keyboard.pressKey("paste");
+        }
+
+        // Next action setup
+
+        while (!userInput.equalsIgnoreCase("quit")) {
+            System.out.println("\nWhat would you like to do now 'copy'/'cut'/'paste'/'redo'/'undo'/'quit'?");
+            userInput = inputScanner.nextLine();
+
+            switch (userInput.toLowerCase()) {
+                case "copy":
+                    System.out.println("\nPick a word in the greeting to copy!");
+                    userInput = inputScanner.nextLine();
+                    start = text.getTextBlock().indexOf(userInput);
+                    end = start + userInput.length();
+                    keyboard.setCommand("copy", new CopyCommand(text, start, end));
+                    keyboard.pressKey("copy");
+                    break;
+                case "cut":
+                    System.out.println("\nPick a word in the greeting to cut!");
+                    userInput = inputScanner.nextLine();
+                    start = text.getTextBlock().indexOf(userInput);
+                    end = start + userInput.length();
+                    keyboard.setCommand("cut", new CutCommand(text, start, end));
+                    keyboard.pressKey("cut");
+                    break;
+                case "paste":
+                    System.out.println("\nWhat index would you like to paste to?");
+                    paste = inputScanner.nextInt();
+                    inputScanner.nextLine();
+                    keyboard.setCommand("paste", new PasteCommand(text, paste));
+                    keyboard.pressKey("paste");
+                    break;
+                case "undo":
+                    keyboard.undoKey();
+                    break;
+                case "redo":
+                    keyboard.redoKey();
+                    break;
+                case "quit":
+                    return;
+                default:
+                    System.out.println("Unknown command");
+            }
+
+            // Action proof
+            System.out.println("\nOur clip board");
+            System.out.println("\"" + text.getClipBoard() + "\"");
+            System.out.println("\nOur current text:");
+            System.out.println(text.getTextBlock());
+        }
+    }
+}