Implement Duke Level 7

Add ability to save and load tasks on the hard drive.

.gitignore

@@ -15,3 +15,4 @@ bin/
 
 /text-ui-test/ACTUAL.txt
 text-ui-test/EXPECTED-UNIX.TXT
+data/duke.txt

src/main/java/Deadline.java

@@ -10,6 +10,11 @@ public Deadline(String taskName, String taskDate) {
         this(taskName, taskDate, false);
     }
 
+    @Override
+    public String toSaveFormat() {
+        return String.format("D, %d, %s, %s", isDone() ? 1 : 0, getTaskName(), taskDate);
+    }
+
     @Override
     public String toString() {
         return String.format("[D]%s (by: %s)", super.toString(), taskDate);

src/main/java/Duke.java

@@ -1,12 +1,23 @@
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.file.FileAlreadyExistsException;
 import java.util.ArrayList;
 import java.util.Scanner;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.Files;
 
 public class Duke {
 
     private static final String DUKE = "\nDuke:";
     private static final String USER = "\nUser:";
     private static ArrayList<Task> tasks = new ArrayList<>();
 
+    private static String dir = System.getProperty("user.dir");
+    private static Path path = Paths.get(dir, "data");
+    private static Path savePath = Path.of(path.toString(),"duke.txt");
+
     public static void main(String[] args) throws DukeException {
 
         String logo = " ____        _        \n"
@@ -15,6 +26,25 @@ public static void main(String[] args) throws DukeException {
                 + "| |_| | |_| |   <  __/\n"
                 + "|____/ \\__,_|_|\\_\\___|\n";
         System.out.println("Hello from\n" + logo);
+
+        try {
+            Files.createDirectory(path);
+        } catch (FileAlreadyExistsException e) {
+            // ignore this exception
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        if (Files.exists(savePath))
+            loadTasks(savePath);
+        else {
+            try {
+                Files.createFile(savePath);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+
         System.out.println(DUKE + "Hi, what do you want from me?\n");
 
         Scanner scanner = new Scanner(System.in);
@@ -78,6 +108,7 @@ private static void listTasks() {
 
     private static void completeTask(int taskNum) {
         tasks.get(taskNum - 1).setDone(true);
+        saveTasks(savePath);
         System.out.println(DUKE + "\n\tMarking task as completed:");
         System.out.printf("\t\t%s\n", tasks.get(taskNum - 1));
     }
@@ -103,10 +134,53 @@ else if (taskType == TaskType.TODO) {
 
     private static void addNewTask(Task newTask) {
         tasks.add(newTask);
+        saveTasks(savePath);
         System.out.println(DUKE + "\n\tAdded:\n\t\t" + newTask);
         System.out.println("\tNow you have " + tasks.size() + " tasks in the list.");
     }
 
+    private static void saveTasks(Path savePath) {
+        try {
+            BufferedWriter writer = Files.newBufferedWriter(savePath);
+            for (Task t: tasks) {
+                writer.write(t.toSaveFormat() + "\n");
+            }
+            writer.close();
+        } catch(IOException ex){
+            ex.printStackTrace();
+        }
+    }
+
+    private static void loadTasks(Path savePath) {
+        try (BufferedReader reader = Files.newBufferedReader(savePath)) {
+            String line = null;
+            Scanner saveDataScanner;
+            while ((line = reader.readLine()) != null) {
+                saveDataScanner = new Scanner(line).useDelimiter(", ");
+                String taskType = saveDataScanner.next();
+                boolean isTaskDone = saveDataScanner.nextInt() == 1;
+                String taskDesc = saveDataScanner.next();
+                switch (taskType) {
+                    case "T":
+                        tasks.add(new ToDo(taskDesc, isTaskDone));
+                        break;
+                    case "D":
+                        tasks.add(new Deadline(taskDesc, saveDataScanner.next(), isTaskDone));
+                        break;
+                    case "E":
+                        tasks.add(new Event(taskDesc, saveDataScanner.next(), isTaskDone));
+                        break;
+                }
+                saveDataScanner.close();
+            }
+            reader.close();
+            System.out.println(DUKE + "I have loaded your past tasks list!");
+            listTasks();
+        } catch (IOException ex) {
+            ex.printStackTrace();
+        }
+    }
+
     private static void printErrorMessage(String message) {
         System.out.println(DUKE);
         System.out.println("\tError: " + message + ".");

src/main/java/Event.java

@@ -10,6 +10,11 @@ public Event(String taskName, String taskDate) {
         this(taskName, taskDate, false);
     }
 
+    @Override
+    public String toSaveFormat() {
+        return String.format("E, %d, %s, %s", isDone() ? 1 : 0, getTaskName(), taskDate);
+    }
+
     @Override
     public String toString() {
         return String.format("[E]%s (at: %s)", super.toString(), taskDate);

src/main/java/Task.java

@@ -3,6 +3,8 @@ public abstract class Task {
     private TaskType taskType;
     private boolean isDone;
 
+    public abstract String toSaveFormat();
+
     public Task(String taskName, TaskType taskType, boolean isDone) {
         this.taskName = taskName;
         this.taskType = taskType;
@@ -21,6 +23,10 @@ public void setTaskName(String taskName) {
         this.taskName = taskName;
     }
 
+    public TaskType getTaskType() {
+        return taskType;
+    }
+
     public boolean isDone() {
         return isDone;
     }

src/main/java/ToDo.java

@@ -7,6 +7,11 @@ public ToDo(String taskName) {
         this(taskName, false);
     }
 
+    @Override
+    public String toSaveFormat() {
+        return String.format("T, %d, %s", isDone() ? 1 : 0, getTaskName());
+    }
+
     @Override
     public String toString() {
         return String.format("[T]%s", super.toString());