Exception Factory

Create Exception instances with Factory-methods and Builder patterns!

Import the Dependency

xml <dependency> <groupId>io.github.chrimle</groupId> <artifactId>exception-factory</artifactId> <version>0.4.0</version> </dependency>

Example Usage

There are several ways of instantiating Exceptions using exception-factory. Here are some examples, given in the order of quick-and-easy to more customized Exceptions.

1. Using ExceptionFactory

Offers the creation of IllegalArgumentExceptions and IllegalStateExceptions, in the following ways:

```java import io.github.chrimle.exceptionfactory.ExceptionFactory; import io.github.chrimle.exceptionfactory.MessageTemplates;

import java.util.regex.Pattern;

import static io.github.chrimle.exceptionfactory.MessageTemplates.OneArgTemplate.*; import static io.github.chrimle.exceptionfactory.MessageTemplates.TwoArgTemplate.MUSTMATCHREGEX;

// Example of ExceptionFactory static { // Example of a One-Arg MessageTemplate, which throws "username MUST NOT be null". if (username == null) throw ExceptionFactory.illegalArgumentOf("username", MUSTNOTBE_NULL);

// Example of a Two-Arg MessageTemplate, which throws "username MUST match the RegEx ^[a-z]{3,15}$". if (!Pattern.matches("^[a-z]{3,15}$", username)) throw ExceptionFactory.illegalArgumentOf("username", MUSTMATCHREGEX, "^[a-z]{3,15}$"); } `` Refer to [MessageTemplates](src/main/java/io/github/chrimle/exceptionfactory/MessageTemplates.java) for all available *message templates*. These are separated by how many *format specifiers* are needed, i.e.OneArgTemplaterequires ***one*** argument to format the resultingString`. For custom messages, and/or providing a cause, see section below.

2. Using ExceptionBuilder

Offers the creation of any Exception-class, via a builder-pattern. This class is used by ExceptionFactory internally.

```java import io.github.chrimle.exceptionfactory.ExceptionBuilder; import io.github.chrimle.exceptionfactory.MessageTemplates;

import static io.github.chrimle.exceptionfactory.MessageTemplates.TwoArgTemplate.*;

// Example of ExceptionBuilder

static { if (1 + 1 == 3) { // Creating a plain Exception without message/cause. throw ExceptionBuilder.of(MakesNoSenseException.class).build(); }

try { oldUsername = userRepository.getUsername(userId); } catch (NoSuchUserException exception) { // Creating an exception with a custom message and cause. throw ExceptionBuilder.of(IllegalArgumentException.class) .setMessage("No user with userId '%s' exists!"::formatted, userId) .setCause(exception) .build(); } catch (ExceptionalException exception) { // Creating an exception with a custom format message string and cause. throw ExceptionBuilder.of(IllegalStateException.class) .setMessage("No clue what happened. Time to log everything %s, %s, %s, %s, %s", userId, newUsername, newLanguage, newDescription) .setCause(exception) .build(); }

// Creating an exception with a MessageTemplate. (Similar to ExceptionFactory) if (newUsername == oldUsername) throw ExceptionBuilder.of(IllegalArgumentException.class) .setMessage(MUSTNOTBEEQUALTO, "newUsername", oldUsername) .build(); } ```

JavaDocs

Please refer to the JavaDocs for further explanations.