net.ninjacat.smooth.utils

Class Try<T>

java.lang.Object

net.ninjacat.smooth.utils.Try<T>

public abstract class Try<T>
extends Object

Wrapper around potentially unsafe execution.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Try.FunctionExecutor<R,P> Delayed function executor.

Method Summary

Modifier and Type	Method and Description
static <T> Try<T>	execute(Callable<T> code) Executes code supplied as Callable.
static <P,T> Try.FunctionExecutor<T,P>	execute(Func<T,P> func) Executes unary function
static <T> Try<T>	failure(Throwable fail) Creates a failed Try instance.
Option<T>	get() Retrieves result of computation from Try wrapped in Option.
abstract Throwable	getFailure()
abstract T	getValue()
abstract boolean	isSuccessful()
Try<T>	recover(Callable<T> recoverCode) Tries to recover from failure with provided Callable.
static <T> Try<T>	success(T value) Creates a successful Try instance.
<S> Try<S>	then(Func<S,T> mapper) Allows chaining of several operations depending on result of the previous one.

Methods inherited from class java.lang.Object

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

Method Detail

execute

public static <T> Try<T> execute(Callable<T> code)

Executes code supplied as Callable.

Type Parameters:

T - type of resulting value

Parameters:

code - Callable to execute

Returns:

Either Try.Success if execution was successful or Try.Failure if execution has thrown the exception.

success

public static <T> Try<T> success(T value)

Creates a successful Try instance.

Type Parameters:

T - Type of the value

Parameters:

value - Value of the Try

Returns:

Successful result

failure

public static <T> Try<T> failure(Throwable fail)

Creates a failed Try instance.

Type Parameters:

T - Type of the possible result

Parameters:

fail - Throwable of the failure

Returns:

Failed result

execute

public static <P,T> Try.FunctionExecutor<T,P> execute(Func<T,P> func)

Executes unary function

Usage:
Try.execute(function).with(42);

Allows to create a

Type Parameters:

P - type of parameter

T - type of result

Parameters:

func - function to be executed

Returns:

delayed function execution which can be executed by supplying it with parameter.

isSuccessful

public abstract boolean isSuccessful()

Returns:

true if execution was successful

getValue

public abstract T getValue()

Returns:

value of the execution

Throws:

IllegalStateException - if execution was not successful. Use isSuccessful() to check execution status.

getFailure

public abstract Throwable getFailure()

Returns:

exception which caused failure

Throws:

IllegalStateException - if execution was successful. Use isSuccessful() to check execution status.

then

public <S> Try<S> then(Func<S,T> mapper)

Allows chaining of several operations depending on result of the previous one. Hides complexity of error-handling and allows developer to focus on happy path.

Usage example:

Try<Integer> result = Try.execute(DeepThought).with("What is the answer to the ultimate question?").then(interpretAnswer);

This code will execute function DeepThough which accepts string as a parameter and then pass its result to function interpretAnswer, which returns int.

If both of the functions execute successfully then result will be Try.Success containing an integer, if any of the functions fail with exception then result will be Try.Failure containing exception. This code will never crash.

Type Parameters:

S - type of returning value of mapper function

Parameters:

mapper - function which accepts value from this object.

Returns:

result of execution of mapper function wrapped in Try

recover

public Try<T> recover(Callable<T> recoverCode)

Tries to recover from failure with provided Callable. If original Try.execute() call was successful, no recovery is performed

Parameters:

recoverCode - Callable to call in the event of failure

Returns:

Either Try.Success or Try.Failure

get

public Option<T> get()

Retrieves result of computation from Try wrapped in Option. If execution was successful it will return it, otherwise Option.absent() will be returned.

Returns:

Optional result of computation.