Listing tasks

Learn to print tasks formatted with listTasks.

The listTasks method

Now we add a listTasks method to the TodoList. It prints every task numbered, so the user can see what is in the list.

The method is declared as void listTasks(). Inside, a for loop walks the tasks list and prints each task with print.

Example: for (var i = 0; i < tasks.length; i++) { print(tasks[i].title); }. This prints only the title of each task. You can also add the index or status; the task in this lesson will ask for the index.

Numbered list

To print tasks numbered, use the loop index. Example: print('${i + 1}. ${tasks[i].title}'). This yields output like '1. Read a book'.

String interpolation puts expressions inside ${...}. i + 1 starts the count at 1; programmers count from 0, so we add 1 to show users '1, 2, 3'.

This small touch makes the list readable. Later we can add the completion status; but first the bare list matters.

Exercise Add the listTasks method

Add a void listTasks() method to the TodoList class. Inside, loop over tasks with a for loop and print each task as '${i + 1}. ${tasks[i].title}' with print. Inside main add list.addTask('Kitap oku') and list.listTasks() calls.

Show example solution

class Task {
  String title;
  bool done = false;
  Task(this.title);
}

class TodoList {
  List<Task> tasks = [];
  void addTask(String title) {
    tasks.add(Task(title));
  }
  void listTasks() {
    for (var i = 0; i < tasks.length; i++) {
      print('${i + 1}. ${tasks[i].title}');
    }
  }
}

void main() {
  var list = TodoList();
  list.addTask('Kitap oku');
  list.listTasks();
}

Test yourself

The for loop

void listTasks() {
  for (var i = 0; i < tasks.____; i++) {
    print(tasks[i].title);
  }
}

Show answer

void listTasks() {
  for (var i = 0; i < tasks.length; i++) {
    print(tasks[i].title);
  }
}

Match the loop parts

for

Loop keyword
var i = 0

Init
i < tasks.length

Condition
i++

Step
What does tasks[i] return?
- The first Task
- The Task at index i
- Throws
- The list length
Show answer

The Task at index i — tasks[i] returns the Task at index i.

Next lesson: Completing tasks

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