Adding tasks

Add tasks with addTask.

Adding tasks: the addTask method

Now we will set up a second class called TodoList. This class keeps tasks in an ArrayList<Task> and adds new tasks with the addTask method.

class TodoList {
  ArrayList<Task> tasks = new ArrayList<>();
  void addTask(String title) {
    tasks.add(new Task(title));
  }
}

The addTask method creates a new Task object and adds it to the list. So the caller only provides the title; object creation stays hidden inside the method.

TodoList and Task together

The TodoList class stores Task objects in a list. The addTask method adds one element per call.

TodoList list = new TodoList();
list.addTask("Shopping");
list.addTask("Homework");
System.out.println(list.tasks);
// [[ ] Shopping, [ ] Homework]

When we print the list directly, we see all tasks inside brackets. Later we will produce a more readable output with the listTasks method.

Exercise Write the addTask method

Inside the TodoList class, define void addTask(String title); the body should call tasks.add(new Task(title)). In main, call list.addTask("Shopping") and list.addTask("Homework"), then print with System.out.println(list.tasks).

Show example solution

// inside TodoList:
void addTask(String title) {
  tasks.add(new Task(title));
}
// inside main:
list.addTask("Shopping");
list.addTask("Homework");
System.out.println(list.tasks);

Test yourself

Fill in the blank: add to the list

void addTask(String title) {
  tasks.____(new Task(title));
}

Show answer

void addTask(String title) {
  tasks.add(new Task(title));
}

Match call to result

addTask("X")

X is added to the list
list.tasks

The list of all tasks
new Task(title)

A new task object
System.out.println(list.tasks)

Bracketed output
What should the return type of addTask be?
- int
- void
- Task
- String
Show answer

int — addTask returns nothing; it only appends.

Next lesson: Listing tasks

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