Java

What is the Difference Between Java Fields and Java Methods?

In Java, fields and methods make up the building blocks of object-oriented programming. Java fields represent the state of an object, while methods represent the behavior or actions that an object can perform. Methods can take parameters that are used to modify their behavior or return values, while fields cannot take parameters.

This article will illustrate the Java fields and methods along with the key difference in detail:

What are Java Fields?

Java Fields, also known as instance variables or class variables, are the variables defined inside a class that holds data or state. Fields represent the state of an object and can be used to store information that is specific to that object.

Fields can be accessed and modified by methods within the same class or by objects of that class. Fields can also be accessed and modified by methods in other classes if the field is declared with a public access modifier. Private fields, on the other hand, can only be accessed and modified within the same class.

Syntax

The syntax for declaring a Java field is as follows:

access_modifier data_type field_name;

The description of the above syntax is mentioned below:

  • The “access_modifier” specifies the visibility of the field,
  • The “data_type” specifies the type of data that the field can hold.
  • The “field_name” is the name given to the field.

Example

Here’s an example of declaring a Java field:

public class Person {

private String name;

public int age;

}

In this example,

  • A class “Person” is defined with two fields: name and age.
  • The “name” field is declared using the private access modifier, indicating that it can only be accessed within the same class.
  • While the “age” field is declared with a public access modifier, meaning it can be accessed from outside the class.

What are Java Methods?

Java methods, also known as member functions or procedures, are the actions or operations that an object can perform. They are defined inside a class and can access the fields of that class. Methods can be called on objects of a class and can perform operations on the fields of that object. Methods can also be used to modify the state of an object by changing the values of its fields. Methods can be public, private, or protected, depending on their visibility requirements.

Syntax

The syntax for declaring a Java method is as follows:

access_modifier return_type method_name(parameter_list) {

// method body

}

Here,

  • access_modifier” specifies the visibility of the method.
  • return_type” defines the type of data that the method returns.
  • method_name” is the name given to the method.
  • parameter_list” specifies the inputs or arguments that the method accepts.

Example

Here’s an example of declaring a Java method:

public class Calculator {

public int add (int a, int b) {

int result = a + b;

return result;

}

}

In this example,

  • A class “Calculator” is defined with a method “add()” that accepts two integer parameters and returns their sum.
  • The method is declared with the public access modifier and an int return type.

Now, create an object of the Calculator class and call the add() method as follows:

Calculator calc = new Calculator();

int sum = calc.add(5, 10);

System.out.println(sum); // Output: 15

The further part of code snippets is explained below:

  • Create an object of the “Calculator” class and call the add () method, passing it two integer arguments.
  • The method returns the “sum” of the arguments, which store in a variable sum and print to the console.

What is the Difference Between Java Fields and Java Methods?

In Java, fields and methods are both components of a class that can be used to define the behavior and data of objects instantiated from that class. However, there are some key differences between them:

Purpose: Fields are used to store data that belongs to an object, whereas methods are used to define the behavior of the object.

Access: Fields can be accessed directly from other objects or classes, while methods can only be accessed through an object’s public interface.

Modifiability: Fields can be modified directly by other objects or classes, while methods can only be modified by the class that defines them.

Parameters: Methods can take parameters that are used to modify their behavior or return values, while fields cannot take parameters.

Return value: Methods can return a value, while fields cannot.

Conclusion

Java fields are used to store data, while Java methods are used to define behavior. Fields are accessed directly and can be modified directly. On the other hand, methods are accessed through a public interface and can only be modified by the class that defines them. Methods can take parameters and return values, while fields cannot.

About the author

Syed Minhal Abbas

I hold a master's degree in computer science and work as an academic researcher. I am eager to read about new technologies and share them with the rest of the world.