Add read/write functionalities such that users can load their own tas…

…k lists from their hard disks and save changes they made to their lists on their hard disks

data/duke.txt

@@ -0,0 +1,5 @@
+T|0|deadline
+D|0|eat lunc|noon
+D|0|lunc|tomorrow
+T|0|lunch
+T|0|lunch

src/main/java/Deadline.java

@@ -12,4 +12,9 @@ public String toString() {
         return "[D]" + super.toString() + " (by: " + by + ")";
     }
 
+    @Override
+    public String getDetails() {
+        return "D|" + (isDone ? "1" : "0") + "|" + description + "|" + by;
+    }
+
 }

src/main/java/Event.java

@@ -11,4 +11,9 @@ public Event(String description, String at) {
     public String toString() {
         return "[E]" + super.toString() + " (at: " + at + ")";
     }
+
+    @Override
+    public String getDetails() {
+        return "E|" + (isDone ? "1" : "0") + "|" + description + "|" + at;
+    }
 }

src/main/java/FileEditor.java

@@ -0,0 +1,38 @@
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.util.Scanner;
+
+public class FileEditor {
+    private static final String DIRECTORY = "data";
+    private static final String FILENAME = "duke.txt";
+    private static final String FILEPATH = DIRECTORY + File.separator + FILENAME;
+
+    public static void updateFile(ArrayList<Task> tasks) throws IOException {
+        FileWriter fw = new FileWriter(FILEPATH);
+        for (Task task : tasks) {
+            String taskToAppend = task.getDetails();
+            fw.write(taskToAppend + System.lineSeparator());
+        }
+        fw.close();
+    }
+
+    public ArrayList<String> readFileContents() throws IOException {
+        File directory = new File(DIRECTORY);
+        if(!directory.exists()) {
+            directory.mkdir();
+        }
+        File file = new File(DIRECTORY + File.separator + FILENAME);
+        if(!file.exists()) {
+            file.createNewFile();
+        }
+        Scanner s = new Scanner(file);
+        ArrayList<String> tasksFromFile = new ArrayList<>();
+        while (s.hasNextLine()) {
+            tasksFromFile.add(s.nextLine());
+        }
+        return tasksFromFile;
+    }
+}

src/main/java/Task.java

@@ -1,4 +1,4 @@
-public class Task {
+public abstract class Task {
     protected String description;
     protected boolean isDone;
 
@@ -8,7 +8,7 @@ public Task(String description) {
     }
 
     public String getStatusIcon() {
-        return (isDone ? "X" : " "); // mark done task with X
+        return (isDone ? "X" : " ");
     }
 
     public String getDescription() {
@@ -43,4 +43,6 @@ public String toString() {
         return "[" + getStatusIcon() + "] " + description;
     }
 
+    public abstract String getDetails();
+
 }

src/main/java/Todo.java

@@ -8,4 +8,9 @@ public Todo(String description) {
     public String toString() {
         return "[T]" + super.toString();
     }
+
+    @Override
+    public String getDetails() {
+        return "T|" + (isDone ? "1" : "0") + "|" + description;
+    }
 }