Package io.earcam.unexceptional

Class Closing

java.lang.Object

io.earcam.unexceptional.Closing

public final class Closing
extends Object

Succinctly handle AutoCloseables that throw checked Exceptions.

There are two families of static methods; closeAfterApplying(...) and closeAfterAccepting(...), the former applies checked functions (the use-case being read) while the later accepts checked consumers (the use-case being write)

Example: this zero-branch, single-instruction, one-liner will find a free port number:

int port = Closing.closeAfterApplying(ServerSocket::new, 0, ServerSocket::getLocalPort);

Motivation: I/O stream instances typically (and necessarily) requires handling a lot of possible IOExceptions - by invoking:

• Constructor
• A read/write call
• A call to AutoCloseable.close()
• A read/write call, then subsequently in the call to AutoCloseable.close() - via try-with-resources

That's a lot of branches to cover - often it is irrelevant to the application which branch actually throws, but regardless test coverage suffers without some needless stub/mocked throw-on-create/read/write/close tests.

Since:

0.3.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Closing.AutoClosed<T,E extends Exception>

Method Summary

Modifier and Type	Method and Description
static <T,E extends Exception> Closing.AutoClosed<T,E>	autoClosing(T instance, CheckedConsumer<T,E> closeMethod) Reshape instances to fit try-catch autoclose.
static <C extends AutoCloseable> void	closeAfterAccepting(C closeable, CheckedConsumer<C,?> consume) Consumes the closeable before closing.
static <C extends AutoCloseable,T> void	closeAfterAccepting(CheckedFunction<T,C,?> create, T t, CheckedConsumer<C,?> consume) Applies the create function to t, resulting in a AutoCloseable which is closed after being consumed.
static <C extends AutoCloseable,T,U> void	closeAfterAccepting(CheckedFunction<T,C,?> create, T t, U instance, CheckedBiConsumer<C,U,?> consume)
static <C extends AutoCloseable,U> void	closeAfterAccepting(C closeable, U instance, CheckedBiConsumer<C,U,?> consume) Consumes both the closeable and instance before closing.
static <C extends AutoCloseable,R> R	closeAfterApplying(C closeable, CheckedFunction<C,R,?> convert) Applies the function to the closeable, returning the result and closing the closable - checked exceptions are rethrown as unchecked.
static <C extends AutoCloseable,T,R> R	closeAfterApplying(CheckedFunction<T,C,?> create, T t, CheckedFunction<C,R,?> convert) Ultra-shorthand for AutoCloseable/Closeable, obvious use for InputStream
static <C extends AutoCloseable,U,R,E extends Throwable> R	closeAfterApplying(C closeable, U instance, CheckedBiFunction<C,U,R,E> convert) Applies the bi-function to the closeable, returning the result and closing the closable - checked exceptions are rethrown as unchecked.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

closeAfterApplying

public static <C extends AutoCloseable,T,R> R closeAfterApplying(CheckedFunction<T,C,?> create,
                                                                 T t,
                                                                 CheckedFunction<C,R,?> convert)

Ultra-shorthand for AutoCloseable/Closeable, obvious use for InputStream

Type Parameters:

C - AutoCloseable type

T - create function argument type

R - the result type

Parameters:

create - a function applying t to produce an AutoCloseable of type <C>

t - the argument to apply to the create function

convert - a function applied to the AutoCloseable to produce the result

Returns:

the result of applying the convert function

closeAfterApplying

public static <C extends AutoCloseable,R> R closeAfterApplying(C closeable,
                                                               CheckedFunction<C,R,?> convert)

Applies the function to the closeable, returning the result and closing the closable - checked exceptions are rethrown as unchecked.

Type Parameters:

C - the auto-closeable type, to apply and close

R - the result type

Parameters:

closeable - the closeable subject of the convert function

convert - the function consuming the closeable and supplying the result

Returns:

the result of applying convert function to the closeable argument

closeAfterApplying

public static <C extends AutoCloseable,U,R,E extends Throwable> R closeAfterApplying(C closeable,
                                                                                     U instance,
                                                                                     CheckedBiFunction<C,U,R,E> convert)

Applies the bi-function to the closeable, returning the result and closing the closable - checked exceptions are rethrown as unchecked.

Type Parameters:

C - the auto-closeable type, will be applied and closed

U - the type of second argument to bi-function apply

R - the result type

Parameters:

closeable - the closeable subject of the convert bi-function

instance - the second argument for the bi-function

convert - the function consuming the closeable and supplying the result

Returns:

the result of applying convert function to the closeable argument

closeAfterAccepting

public static <C extends AutoCloseable,T> void closeAfterAccepting(CheckedFunction<T,C,?> create,
                                                                   T t,
                                                                   CheckedConsumer<C,?> consume)

Applies the create function to t, resulting in a AutoCloseable which is closed after being consumed. Checked exceptions are rethrown as unchecked.

Type Parameters:

C - the auto-closeable type, to be created, consumed and closed

T - the function's argument type, used to create the auto-closeable

Parameters:

create - the function creating the AutoCloseable

t - the argument that the create function is applied to

consume - the consumer of the AutoCloseable

closeAfterAccepting

public static <C extends AutoCloseable> void closeAfterAccepting(C closeable,
                                                                 CheckedConsumer<C,?> consume)

Consumes the closeable before closing. Checked exceptions are rethrown as unchecked.

Type Parameters:

C - the auto-closeable type

Parameters:

closeable - the closeable to be consumed and closed

consume - the consumer of the AutoCloseable

closeAfterAccepting

public static <C extends AutoCloseable,T,U> void closeAfterAccepting(CheckedFunction<T,C,?> create,
                                                                     T t,
                                                                     U instance,
                                                                     CheckedBiConsumer<C,U,?> consume)

closeAfterAccepting

public static <C extends AutoCloseable,U> void closeAfterAccepting(C closeable,
                                                                   U instance,
                                                                   CheckedBiConsumer<C,U,?> consume)

Consumes both the closeable and instance before closing. Checked exceptions are rethrown as unchecked.

Type Parameters:

C - the auto-closeable type to consume

U - the type of consumer's second argument

Parameters:

closeable - the closeable to be consumed and closed

instance - the instance to consume

consume - the consumer of the AutoCloseable

autoClosing

public static <T,E extends Exception> Closing.AutoClosed<T,E> autoClosing(T instance,
                                                                          CheckedConsumer<T,E> closeMethod)

Reshape instances to fit try-catch autoclose. Example usage: try(AutoClosed vm = Closing.autoClosing(getCurrentVm(), VirtualMachine::detach)) { vm.get().loadAgent(x, y); }

Parameters:

instance -

closeMethod -

Returns:

Since:

0.5.0