☕Java Programming

Java Class Attributes

Updated 2026-05-12

15 min read

Java Class Attributes

In object-oriented programming, attributes are variables that hold data specific to an object. Understanding how to manage these attributes is crucial for creating robust and maintainable Java programs. This tutorial will guide you through accessing, modifying, and handling multiple attributes within a class.

Introduction

Attributes in Java classes represent the state of an object. They can be accessed and modified using methods or directly (with appropriate access modifiers). Proper management of attributes ensures encapsulation, which is a fundamental principle of OOP. This tutorial will cover:

Accessing Attributes: How to retrieve attribute values.
Modifying Attributes: Techniques for changing attribute values.
Multiple Attributes: Managing multiple attributes within a class.

Accessing Attributes

Attributes can be accessed using the dot notation (.) on an object instance. The access depends on the attribute's visibility (public, private, protected).

Example: Accessing Public Attributes

Java

1class Car {
2  public String color;
3  public int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  };
9}
10 
11public class Main {
12  public static void main(String[] args) {
13      Car myCar = new Car("Red", 2020);
14      System.out.println("Color: " + myCar.color);
15      System.out.println("Year: " + myCar.year);
16  }
17}

Output

Color: Red
Year: 2020

Example: Accessing Private Attributes

Private attributes cannot be accessed directly from outside the class. They require public getter methods.

Java

1class Car {
2  private String color;
3  private int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  }
9 
10  public String getColor() {
11      return color;
12  }
13 
14  public int getYear() {
15      return year;
16  }
17}
18 
19public class Main {
20  public static void main(String[] args) {
21      Car myCar = new Car("Blue", 2018);
22      System.out.println("Color: " + myCar.getColor());
23      System.out.println("Year: " + myCar.getYear());
24  }
25}

Output

Color: Blue
Year: 2018

Modifying Attributes

Attributes can be modified using setter methods or directly (for public attributes).

Example: Modifying Public Attributes

Java

1class Car {
2  public String color;
3  public int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  }
9}
10 
11public class Main {
12  public static void main(String[] args) {
13      Car myCar = new Car("Green", 2019);
14      System.out.println("Original Color: " + myCar.color);
15 
16      // Modify the attribute
17      myCar.color = "Yellow";
18      System.out.println("Modified Color: " + myCar.color);
19  }
20}

Output

Original Color: Green
Modified Color: Yellow

Example: Modifying Private Attributes

Private attributes should be modified using setter methods.

Java

1class Car {
2  private String color;
3  private int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  }
9 
10  public void setColor(String color) {
11      this.color = color;
12  }
13 
14  public void setYear(int year) {
15      this.year = year;
16  }
17}
18 
19public class Main {
20  public static void main(String[] args) {
21      Car myCar = new Car("Black", 2017);
22      System.out.println("Original Color: " + myCar.color);
23 
24      // Modify the attribute using setter
25      myCar.setColor("White");
26      System.out.println("Modified Color: " + myCar.color);
27  }
28}

Output

Original Color: Black
Modified Color: White

Multiple Attributes

A class can have multiple attributes, each serving a different purpose. Managing these attributes effectively is crucial for maintaining clean and efficient code.

Example: Handling Multiple Attributes

Java

1class Car {
2  private String make;
3  private String model;
4  private int year;
5 
6  public Car(String make, String model, int year) {
7      this.make = make;
8      this.model = model;
9      this.year = year;
10  }
11 
12  public String getMake() {
13      return make;
14  }
15 
16  public void setMake(String make) {
17      this.make = make;
18  }
19 
20  public String getModel() {
21      return model;
22  }
23 
24  public void setModel(String model) {
25      this.model = model;
26  }
27 
28  public int getYear() {
29      return year;
30  }
31 
32  public void setYear(int year) {
33      this.year = year;
34  }
35}
36 
37public class Main {
38  public static void main(String[] args) {
39      Car myCar = new Car("Toyota", "Corolla", 2021);
40      System.out.println("Make: " + myCar.getMake());
41      System.out.println("Model: " + myCar.getModel());
42      System.out.println("Year: " + myCar.getYear());
43 
44      // Modify attributes
45      myCar.setMake("Honda");
46      myCar.setModel("Civic");
47      myCar.setYear(2022);
48 
49      System.out.println("
50Updated Details:");
51      System.out.println("Make: " + myCar.getMake());
52      System.out.println("Model: " + myCar.getModel());
53      System.out.println("Year: " + myCar.getYear());
54  }
55}

Output

Make: Toyota
Model: Corolla
Year: 2021

Updated Details:
Make: Honda
Model: Civic
Year: 2022

Practical Example

Let's create a practical example that demonstrates the use of multiple attributes, accessors, and mutators.

Java

1class Employee {
2  private String name;
3  private int age;
4  private double salary;
5 
6  public Employee(String name, int age, double salary) {
7      this.name = name;
8      this.age = age;
9      this.salary = salary;
10  }
11 
12  public String getName() {
13      return name;
14  }
15 
16  public void setName(String name) {
17      this.name = name;
18  }
19 
20  public int getAge() {
21      return age;
22  }
23 
24  public void setAge(int age) {
25      if (age > 0) {
26          this.age = age;
27      } else {
28          System.out.println("Invalid age");
29      }
30  }
31 
32  public double getSalary() {
33      return salary;
34  }
35 
36  public void setSalary(double salary) {
37      if (salary >= 0) {
38          this.salary = salary;
39      } else {
40          System.out.println("Invalid salary");
41      }
42  }
43 
44  public void displayInfo() {
45      System.out.println("Name: " + name);
46      System.out.println("Age: " + age);
47      System.out.println("Salary: $" + salary);
48  }
49}
50 
51public class Main {
52  public static void main(String[] args) {
53      Employee emp = new Employee("John Doe", 30, 50000.0);
54      emp.displayInfo();
55 
56      // Modify attributes
57      emp.setName("Jane Doe");
58      emp.setAge(32);
59      emp.setSalary(55000.0);
60 
61      System.out.println("
62Updated Information:");
63      emp.displayInfo();
64  }
65}

Output

Name: John Doe
Age: 30
Salary: $50000.0

Updated Information:
Name: Jane Doe
Age: 32
Salary: $55000.0

Summary

Concept	Description
Accessing Attributes	Use dot notation for public attributes; use getters for private attributes.
Modifying Attributes	Modify public attributes directly; use setters for private attributes.
Multiple Attributes	Manage multiple attributes using separate accessors and mutators.

What's Next?

Now that you understand how to manage class attributes, the next step is to learn about Java Class Methods. Methods define the behaviors of objects and are essential for creating interactive and functional Java applications. Continue your learning journey by exploring methods in Java classes.

Java Class Methods

☕Java Programming

Java Class Attributes

Updated 2026-05-12

15 min read

Java Class Attributes

Introduction

Accessing Attributes: How to retrieve attribute values.
Modifying Attributes: Techniques for changing attribute values.
Multiple Attributes: Managing multiple attributes within a class.

Accessing Attributes

Attributes can be accessed using the dot notation (.) on an object instance. The access depends on the attribute's visibility (public, private, protected).

Example: Accessing Public Attributes

Java

1class Car {
2  public String color;
3  public int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  };
9}
10 
11public class Main {
12  public static void main(String[] args) {
13      Car myCar = new Car("Red", 2020);
14      System.out.println("Color: " + myCar.color);
15      System.out.println("Year: " + myCar.year);
16  }
17}

Output

Color: Red
Year: 2020

Example: Accessing Private Attributes

Private attributes cannot be accessed directly from outside the class. They require public getter methods.

Java

1class Car {
2  private String color;
3  private int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  }
9 
10  public String getColor() {
11      return color;
12  }
13 
14  public int getYear() {
15      return year;
16  }
17}
18 
19public class Main {
20  public static void main(String[] args) {
21      Car myCar = new Car("Blue", 2018);
22      System.out.println("Color: " + myCar.getColor());
23      System.out.println("Year: " + myCar.getYear());
24  }
25}

Output

Color: Blue
Year: 2018

Modifying Attributes

Attributes can be modified using setter methods or directly (for public attributes).

Example: Modifying Public Attributes

Java

1class Car {
2  public String color;
3  public int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  }
9}
10 
11public class Main {
12  public static void main(String[] args) {
13      Car myCar = new Car("Green", 2019);
14      System.out.println("Original Color: " + myCar.color);
15 
16      // Modify the attribute
17      myCar.color = "Yellow";
18      System.out.println("Modified Color: " + myCar.color);
19  }
20}

Output

Original Color: Green
Modified Color: Yellow

Example: Modifying Private Attributes

Private attributes should be modified using setter methods.

Java

1class Car {
2  private String color;
3  private int year;
4 
5  public Car(String color, int year) {
6      this.color = color;
7      this.year = year;
8  }
9 
10  public void setColor(String color) {
11      this.color = color;
12  }
13 
14  public void setYear(int year) {
15      this.year = year;
16  }
17}
18 
19public class Main {
20  public static void main(String[] args) {
21      Car myCar = new Car("Black", 2017);
22      System.out.println("Original Color: " + myCar.color);
23 
24      // Modify the attribute using setter
25      myCar.setColor("White");
26      System.out.println("Modified Color: " + myCar.color);
27  }
28}

Output

Original Color: Black
Modified Color: White

Multiple Attributes

A class can have multiple attributes, each serving a different purpose. Managing these attributes effectively is crucial for maintaining clean and efficient code.

Example: Handling Multiple Attributes

Java

1class Car {
2  private String make;
3  private String model;
4  private int year;
5 
6  public Car(String make, String model, int year) {
7      this.make = make;
8      this.model = model;
9      this.year = year;
10  }
11 
12  public String getMake() {
13      return make;
14  }
15 
16  public void setMake(String make) {
17      this.make = make;
18  }
19 
20  public String getModel() {
21      return model;
22  }
23 
24  public void setModel(String model) {
25      this.model = model;
26  }
27 
28  public int getYear() {
29      return year;
30  }
31 
32  public void setYear(int year) {
33      this.year = year;
34  }
35}
36 
37public class Main {
38  public static void main(String[] args) {
39      Car myCar = new Car("Toyota", "Corolla", 2021);
40      System.out.println("Make: " + myCar.getMake());
41      System.out.println("Model: " + myCar.getModel());
42      System.out.println("Year: " + myCar.getYear());
43 
44      // Modify attributes
45      myCar.setMake("Honda");
46      myCar.setModel("Civic");
47      myCar.setYear(2022);
48 
49      System.out.println("
50Updated Details:");
51      System.out.println("Make: " + myCar.getMake());
52      System.out.println("Model: " + myCar.getModel());
53      System.out.println("Year: " + myCar.getYear());
54  }
55}

Output

Make: Toyota
Model: Corolla
Year: 2021

Updated Details:
Make: Honda
Model: Civic
Year: 2022

Practical Example

Let's create a practical example that demonstrates the use of multiple attributes, accessors, and mutators.

Java

1class Employee {
2  private String name;
3  private int age;
4  private double salary;
5 
6  public Employee(String name, int age, double salary) {
7      this.name = name;
8      this.age = age;
9      this.salary = salary;
10  }
11 
12  public String getName() {
13      return name;
14  }
15 
16  public void setName(String name) {
17      this.name = name;
18  }
19 
20  public int getAge() {
21      return age;
22  }
23 
24  public void setAge(int age) {
25      if (age > 0) {
26          this.age = age;
27      } else {
28          System.out.println("Invalid age");
29      }
30  }
31 
32  public double getSalary() {
33      return salary;
34  }
35 
36  public void setSalary(double salary) {
37      if (salary >= 0) {
38          this.salary = salary;
39      } else {
40          System.out.println("Invalid salary");
41      }
42  }
43 
44  public void displayInfo() {
45      System.out.println("Name: " + name);
46      System.out.println("Age: " + age);
47      System.out.println("Salary: $" + salary);
48  }
49}
50 
51public class Main {
52  public static void main(String[] args) {
53      Employee emp = new Employee("John Doe", 30, 50000.0);
54      emp.displayInfo();
55 
56      // Modify attributes
57      emp.setName("Jane Doe");
58      emp.setAge(32);
59      emp.setSalary(55000.0);
60 
61      System.out.println("
62Updated Information:");
63      emp.displayInfo();
64  }
65}

Output

Name: John Doe
Age: 30
Salary: $50000.0

Updated Information:
Name: Jane Doe
Age: 32
Salary: $55000.0

Summary

Concept	Description
Accessing Attributes	Use dot notation for public attributes; use getters for private attributes.
Modifying Attributes	Modify public attributes directly; use setters for private attributes.
Multiple Attributes	Manage multiple attributes using separate accessors and mutators.

What's Next?

Java Class Methods