https://github.com/dbc2201/elons-toy-car
https://github.com/dbc2201/elons-toy-car
exercism-solutions java
Last synced: over 1 year ago
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- Host: GitHub
- URL: https://github.com/dbc2201/elons-toy-car
- Owner: dbc2201
- Created: 2022-03-10T06:28:02.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2022-03-10T06:28:06.000Z (over 4 years ago)
- Last Synced: 2025-02-12T08:39:36.967Z (over 1 year ago)
- Topics: exercism-solutions, java
- Language: HTML
- Homepage: https://exercism.org/tracks/java/exercises/elons-toy-car
- Size: 99.6 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Elon's Toy Car
Welcome to Elon's Toy Car on Exercism's Java Track. If you need help running the tests or submitting your code, check
out `HELP.md`. If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
## Introduction
The primary object-oriented construct in Java is the _class_, which is a combination of data (_fields_) and behavior (_
methods_). The fields and methods of a class are known as its _members_.
Access to members can be controlled through access modifiers, the two most common ones being:
- `public`: the member can be accessed by any code (no restrictions).
- `private`: the member can only be accessed by code in the same class.
You can think of a class as a template for creating instances of that class. To create an instance of a class (also
known as an _object_), the `new` keyword is used:
```java
class Car {
}
// Create two car instances
Car myCar = new Car();
Car yourCar = new Car();
```
Fields have a type and a name (defined in camelCase) and can be defined anywhere in a class (by convention cased in
PascalCase):
```java
class Car {
// Accessible by anyone
public int weight;
// Only accessible by code in this class
private String color;
}
```
One can optionally assign an initial value to a field. If a field does _not_ specify an initial value, it wll be set to
its type's default value. An instance's field values can be accessed and updated using dot-notation.
```java
class Car {
// Will be set to specified value
public int weight = 2500;
// Will be set to default value (0)
public int year;
}
Car newCar = new Car();
newCar.weight; // => 2500
newCar.year; // => 0
// Update value of the field
newCar.year=2018;
```
Private fields are usually updated as a side effect of calling a method. Such methods usually don't return any value, in
which case the return type should be `void`:
```java
class CarImporter {
private int carsImported;
public void ImportCars(int numberOfCars) {
// Update private field from public method
carsImported = carsImported + numberOfCars;
}
}
```
## Instructions
In this exercise you'll be playing around with a remote controlled car, which you've finally saved enough money for to
buy.
Cars start with full (100%) batteries. Each time you drive the car using the remote control, it covers 20 meters and
drains one percent of the battery.
The remote controlled car has a fancy LED display that shows two bits of information:
- The total distance it has driven, displayed as: `"Driven meters"`.
- The remaining battery charge, displayed as: `"Battery at %"`.
If the battery is at 0%, you can't drive the car anymore and the battery display will show `"Battery empty"`.
You have six tasks, each of which will work with remote controlled car instances.
## 1. Buy a brand-new remote controlled car
Implement the (_static_) `ElonsToyCar.buy()` method to return a brand-new remote controlled car instance:
```java
ElonsToyCar car=ElonsToyCar.buy();
```
## 2. Display the distance driven
Implement the `ElonsToyCar.distanceDisplay()` method to return the distance as displayed on the LED display:
```java
ElonsToyCar car=ElonsToyCar.buy();
car.distanceDisplay();
// => "Driven 0 meters"
```
## 3. Display the battery percentage
Implement the `ElonsToyCar.batteryDisplay()` method to return the distance as displayed on the LED display:
```java
ElonsToyCar car=ElonsToyCar.buy();
car.batteryDisplay();
// => "Battery at 100%"
```
## 4. Update the number of meters driven when driving
Implement the `ElonsToyCar.drive()` method that updates the number of meters driven:
```java
ElonsToyCar car=ElonsToyCar.buy();
car.drive();
car.drive();
car.distanceDisplay();
// => "Driven 40 meters"
```
## 5. Update the battery percentage when driving
Update the `ElonsToyCar.drive()` method to update the battery percentage:
```java
ElonsToyCar car=ElonsToyCar.buy();
car.drive();
car.drive();
car.batteryDisplay();
// => "Battery at 98%"
```
## 6. Prevent driving when the battery is drained
Update the `ElonsToyCar.drive()` method to not increase the distance driven nor decrease the battery percentage when the
battery is drained (at 0%):
```java
ElonsToyCar car=ElonsToyCar.buy();
// Drain the battery
// ...
car.distanceDisplay();
// => "Driven 2000 meters"
car.batteryDisplay();
// => "Battery empty"
```
## Source
### Created by
- @mikedamay
### Contributed to by
- @mirkoperillo