Listing tasks

Print tasks with listTasks.

Listing tasks: listTasks

Now we will add a method to TodoList that prints tasks in a readable form: listTasks. This method prints each task on its own line.

void listTasks() {
  for (Task t : tasks) {
    System.out.println(t);
  }
}

The for-each loop puts each Task from the list into the t variable in turn. println(t) then calls the toString method and prints a readable line like [ ] Shopping.

Empty list case

When the list is empty, listTasks prints nothing; the for-each loop runs zero times. This silent behavior is usually what we want.

TodoList empty = new TodoList();
empty.listTasks();
// (the call ends without printing anything)

If you wish, you can print a notice at the top with if (tasks.isEmpty()). For now we keep it simple; you can customize this later.

Exercise Write the listTasks method

Inside the TodoList class, define void listTasks(); the body should walk with for (Task t : tasks) and print each task with System.out.println(t). In main, add two tasks and call list.listTasks().

Show example solution

// inside TodoList:
void listTasks() {
  for (Task t : tasks) {
    System.out.println(t);
  }
}
// inside main:
list.listTasks();

Test yourself

Match part to purpose

for (Task t : tasks)

Walks the list
println(t)

Prints the task
toString

Turns the task into text
tasks

The list of all tasks
What does listTasks do when the list is empty?
- It prints nothing
- It prints null
- It throws an error
- It prints an empty line
Show answer

It prints null — For-each runs zero times on an empty list.

Fill in the blank: listTasks loop

void listTasks() {
  for (Task t : ____) {
    System.out.println(t);
  }
}

Show answer

void listTasks() {
  for (Task t : tasks) {
    System.out.println(t);
  }
}

Next lesson: Completing tasks

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies