Task model
- Java course
- Beginner
- Lesson 83/116
- 6 min
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);
// [ ] ShoppingTo 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.
Practice 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.
Starter code
public class Main {
public static void main(String[] args) {
// Create a Task and print it
}
}
class Task {
// Define title (String) and done (boolean) fields
// Constructor: set title, set done to false
// toString: "[x] title" if done, otherwise "[ ] title"
}Sample 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);Expected output
[ ] Shopping
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the done field when a Task is freshly created?
- 0
- true
- null
- false Correct answer
Explanation: A new task is not yet done, so done is false.
2 Fill in the blank: Task field
class Task {
String title;
____ done;
}class Task {
String title;
boolean done;
}Explanation: done should be a primitive boolean.
3 Match field to initial value
| Term | Meaning |
|---|---|
title |
comes from the parameter |
done |
false |
ArrayList<Task> |
empty list |
int index |
starts at 0 |