Method name of static factory method learned from Java 8

Method names in Java are generally verbs, but ** static factory methods ** may use prepositions and nouns.

What is a static factory method?

A ** static factory method ** is a method that provides an instance instead of a constructor, such as String.valueOf (). Detailed explanations are delegated to ** "Effective Java" ** and the following articles.

About Java's static factory method

Java 8 usage example

Classes added in Java 8 utilize static factory methods as a way to provide instances.

Optional

empty()
Generate an empty Optional
of(T value)
Generate Optional with specified non-null value
ofNullable(T value)
Generate Optional with specified value

Stream

empty()
Generate an empty Stream
of(T... values)
Create a Stream with the specified value as an element

LocalDateTime

from(TemporalAccessor temporal)
Instantiate from another temporal object
now()
Create an instance of the current date and time
of(int year, int month, int dayOfMonth, int hour, int minute)
Create an instance of the specified year, month, day, hour, minute
of(LocalDate date, LocalTime time)
Create an instance of the specified date and time

Generalization

Based on the above example, the method name of the static factory method can be generalized as follows.

Method name	role
empty	Create an empty instance
of	Create an instance of the specified parameter
from	Create an instance from an object of another class

In addition to these, it will be easier for the user to give a method name that suits the purpose, such as ʻof Nullableornow`.

Reference link

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