Task model

Design the Task class.

Task model: the Task class

In this project you will build a to-do app step by step. The first step is to define the Task class that represents a task.

Each task has a title (title) and a completion state (done). done is a boolean field; it starts as false.

Task t = new Task("Shopping");
System.out.println(t);
// [ ] Shopping

To print it, we will write a toString method: [x] if done, otherwise [ ]. This lets you see the task state at a glance in the console.

Readable output with toString

In Java, when you print an object with System.out.println, it shows the class name and address by default. If you write a toString method, the object turns into readable text.

public String toString() {
  return (done ? "[x] " : "[ ] ") + title;
}

Here the ternary operator (cond ? a : b) yields [x] when done is true, otherwise [ ] . Then the title is appended. So println(t) prints [ ] Shopping.

Exercise Define the Task class

Define the Task class: String title and boolean done fields, a Task(String title) constructor (set title, set done to false), and a toString method ("[x] title" if done, otherwise "[ ] title"). In main, create a Task and print it.

Show example solution

class Task {
  String title;
  boolean done;
  Task(String title) {
    this.title = title;
    this.done = false;
  }
  public String toString() {
    return (done ? "[x] " : "[ ] ") + title;
  }
}
// inside main:
Task t = new Task("Shopping");
System.out.println(t);

Test yourself

What is the done field when a Task is freshly created?
- 0
- true
- null
- false
Show answer

false — A new task is not yet done, so done is false.

Fill in the blank: Task field

class Task {
  String title;
  ____ done;
}

Show answer

class Task {
  String title;
  boolean done;
}

Match field to initial value

title

comes from the parameter
done

false
ArrayList<Task>

empty list
int index

starts at 0

Next lesson: Adding tasks

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies