Catalog of Method Types

Query methods

Mutation methods

Helper methods

Get method

Definition: A get method is a query method that returns a (logical) field of the object.

Also known as: Getter.

JDK example: Class Object::getClass(), Object Enumeration::nextElement().

Name example: String Name::component(int), NameEnumeration Name::names().

Prefixes: (If any:) get.

Naming: After the prefix (if any), the name of the field being queried follows.

Boolean query method

Comparison method

Conversion method

Set method

Command method

Initialization method

Factory method

Assertion method



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(Some of this material has been taken from a Java Report paper.)

We distinguish three main categories of method types (query methods, mutation methods, and helper methods) from specific method types of these categories.

query methods
- get method (getter)
  - default value method
- boolean query method
- comparison method
- conversion method (interpretation method)
mutation methods
- set method (setter)
- command method
- initialization method
- finalization method
- configuration method
- constructor
helper methods
- creation method
  - factory method
  - cloning method
  - trading method
  - conversion method (or, is this a query method?)
- assertion method
- logging method

If you want to add method types to this list, let me know!

A query method (aka accessing method) is a method that returns some information about the object being queried. It does not change the object's state. There are four main query method types: get method, boolean query method, comparison method, and conversion method.

Definition:	A boolean query method is a query method that returns a boolean value.
Also known as:	-
JDK example:	boolean Object::equals().
Name example:	boolean Name::isEmpty().
Prefixes:	is, has, may, can, ...
Naming:	After the prefix, the aspect being queried follows.

Definition:	A comparison method is a query method that compares two objects and returns a value that tells you which object is "greater" or "lesser" than the other one according to an ordering criterion.
Also known as:	Comparing method.
JDK example:	boolean Object::equals(Object), int Comparable::compareTo(Object).
Name example:	boolean Name::isEqual(Object).
Prefixes:	If also a boolean query method, see boolean query method.
Naming:	If also a boolean query method, see boolean query method.

Definition:	A conversion method is a query method that returns an object that represents the object being queried using some other (typically simpler) object.
Also known as:	Converter method, interpretation method.
JDK example:	String Object::toString(), int Integer::intValue().
Name example:	String Name::asString(), String Name::asStringWith(char).
Prefixes:	as, to.
Naming:	After the prefix, typically the class name being converted to follows.

A mutation method is a method that changes the object's state (mutates it). Typically, it does not return a value to the client. There are three main mutation method types: set method, command method, and initialization method.

Definition:	A set method is a mutation method that sets a (logical) field of an object to some value.
Also known as:	Setter.
JDK example:	void Thread::setPriority(int), void Vector::addElement(Object).
Name example:	void Name::component(String).
Prefixes:	(If any:) set.
Naming:	After the prefix (if any), the field being changed follows.

Definition:	A command method is a method that executes a complex change to the object's state, typically involving several fields and affecting further related objects.
Also known as:	-
JDK example:	void Object::notify(), void JComponent::repaint().
Name example:	void Name::insert(int i, String c), void Name::remove(int i).
Prefixes:	(If any:) handle, execute, make.
Naming:	-

Definition:	An initialization method is a mutation method that sets some or all fields of an object to an initial value.
Also known as:	-
JDK example:	void LookAndFeel::initialize().
Name example:	void StringName::initialize(), void VectorName::initialize().
Prefixes:	init, initialize.
Naming:	If prefixed with init, typically the name of the object part being initialized follows.

A helper method (aka utility method) is a method that performs some support task for the calling object. A helper method does not change the object's state, but only performs operations on the method arguments. Frequently, a helper method is a static method and provided by some helper (utility) class.

Definition:	A factory method is a helper method that creates an object and returns it to the client.
Also known as:	Object creation method.
JDK example:	String String::valueOf(int), String String::valueOf(double).
Name example:	NameEnumeration Name::names(), Name StringName::newName(String).
Prefixes:	(If any:) new, create, make, build.
Naming:	After the prefix, the product name follows.

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Definition:	An assertion method is a helper method that checks whether a certain condition holds. If the condition holds, it returns silently. If it does not hold, an appropriate exception is thrown.
Also known as:	-
JDK example:	void AccessControlContext::checkPermission(Permission) throws AccessControlException
Name example:	void Name::assertIsValidIndex(int) throws InvalidIndexException.
Prefixes:	assert, check, test.
Naming:	After the prefix, the condition being checked follows.