Java Encapsulation: Implementing Car Class with Getter and Setter Methods

Java Encapsulatiion: Exercise-6 with Solution

Write a Java program to create a class called Car with private instance variables company_name, model_name, year, and mileage. Provide public getter and setter methods to access and modify the company_name, model_name, and year variables. However, only provide a getter method for the mileage variable.

Sample Solution:

Java Code:

// Car.java
// Car Class

class Car {
  private String company_name;
  private String model_name;
  private int year;
  private double mileage;

  public String getCompany_name() {
    return company_name;
  }

  public void setCompany_name(String company_name) {
    this.company_name = company_name;
  }

  public String getModel_name() {
    return model_name;
  }

  public void setModel_name(String model_name) {
    this.model_name = model_name;
  }

  public int getYear() {
    return year;
  }

  public void setYear(int year) {
    this.year = year;
  }

  public double getMileage() {
    return mileage;
  }
}

// Main.java
// Main Class

public class Main {
  public static void main(String[] args) {
    // Create an instance of Car
    Car car = new Car();

    // Set the values using the setter methods
    car.setCompany_name("Chevrolet");
    car.setModel_name("Cruze");
    car.setYear(2009);
    // mileage is not set using the setter method

    // Get the values using the getter methods
    String company_name = car.getCompany_name();
    String model_name = car.getModel_name();
    int year = car.getYear();
    double mileage = car.getMileage();

    // Print the values
    System.out.println("Company Name: " + company_name);
    System.out.println("Model Name: " + model_name);
    System.out.println("Year: " + year);
    System.out.println("Mileage: " + mileage);
  }
}

Sample Output:

Company Name: Chevrolet
Model Name: Cruze
Year: 2009
Mileage: 0.0

Explanation:

In this code, the Car class encapsulates the private instance variables company_name, model_name, year, and mileage. The getCompany_name(), getModel_name(), and getYear() methods are public getter methods that allow other classes to access company_name, model_name, and year, respectively. The corresponding set methods are provided to modify these variables.

The getMileage() method is a public getter method that allows other classes to access mileage values. However, no setter method is provided for mileage, meaning it cannot be modified outside the Car class.

In the Main class, an object car of the Car class is created. Company_name, model_name, and year values are set using the respective setter methods, and then retrieved using the getter methods.

The mileage is then retrieved using the getMileage() method and printed using System.out.println().

Flowchart:

Java Code Editor:

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