A method is a named procedure associated with an object or class in object-oriented programming. In that paradigm a method expresses behavior: it performs actions, computes and returns values, or modifies the state of an object. Methods are central to modeling real-world actions in software and are treated as operations attached to a type rather than as free-standing functions; see object-oriented programming and the notion of an object.

Basic structure and signature

Typical parts of a method include its name, parameter list, return type (if any), and the method body. The signature of a method comprises the name and parameter types and is used to distinguish methods with the same name. For example, a method written in many C-like OOP languages can look like: public int getOne() { return 1; }. That example illustrates several aspects at once: syntax for declaration, a visibility modifier (public), a return type (int) and a simple body that returns a literal value. Similar declaration styles appear in languages such as Java and C#.

Visibility and access control

Methods typically include access modifiers that control where they can be invoked. Common modifiers are public, protected, and private; some languages add package-level or module-level visibility. A public method is callable from outside the defining type, while a private method is accessible only inside the same class or object. These controls are a key part of encapsulation and help protect internal data and implementation details, contributing to data security and robustness.

Kinds of methods and behavior

  • Instance methods operate on an instance (object) and typically access instance fields.
  • Static or class methods belong to the class itself rather than to any particular object.
  • Constructors are special methods used to initialize new objects.
  • Getters and setters are lightweight methods for controlled access to properties.
  • Pure methods have no side effects and return values solely based on their inputs; others may modify object state or perform I/O.

Polymorphism, overloading and invocation

Polymorphism allows different classes to provide their own implementations of a method name. Overriding replaces a superclass method in a subclass, and dynamic dispatch selects the correct implementation at runtime. Overloading lets a class define multiple methods with the same name but different parameter lists. Invocation uses a call expression (for example, obj.method(arg)) that binds the call to a particular method implementation according to visibility, signature, and the runtime type of the receiver.

History and evolution

The modern concept of methods grew from early object-oriented languages. Languages such as Simula and Smalltalk introduced ideas of objects that bundle data with procedures; later mainstream languages adopted and adapted these concepts. Over decades, additional features — reflection, method references, closures, first-class functions and annotations or attributes — broadened how methods are defined, discovered, and invoked.

Uses, examples and notable distinctions

Methods are used for modeling behavior, implementing APIs, handling events in graphical interfaces, and organizing business logic. In practice they range from tiny accessors to large routines coordinating multiple subsystems. When comparing terminology, some languages draw a distinction between a "function" (independent routine) and a "method" (routine tied to an object or class); in languages with first-class functions those lines can blur because functions may be stored as object fields or passed as arguments. Advanced techniques include reflective method invocation, method chaining, and higher-order methods that accept or return other methods.

For more technical reference and examples, follow language-specific documentation and tutorials for Java, C#, and other object-oriented languages. See also links to general OOP material: object-oriented programming overview, definitions of an object, common syntax patterns, language pages such as Java and C#, resources about data security, and primitive type descriptions like integer.