Package net.dv8tion.jda.api.utils

Class Result<T>

java.lang.Object

net.dv8tion.jda.api.utils.Result<T>

Type Parameters:

T - The success type

public class Result<T>
extends Object

Represents a computation or task result.
This result may be a failure or success.

This is a value type and does not implement Object.equals(Object) or Object.hashCode()!

Since:

4.2.1

Method Summary

Modifier and Type	Method	Description
static <E> Result<E>	defer(Supplier<? extends E> supplier)	Creates a result instance from the provided supplier.
Result<T>	expect(Predicate<? super Throwable> predicate)	Throws the wrapped exception if the provided predicate returns true.
static <E> Result<E>	failure(Throwable error)	Creates a failure result.
<U> Result<U>	flatMap(Function<? super T,? extends Result<U>> function)	Composite function to convert a result value to another result.
T	get()	Unwraps the success value of this result.
Throwable	getFailure()	Unwraps the error for this result.
boolean	isFailure()	True if this result is a failure.
boolean	isSuccess()	True if this result is a success.
<U> Result<U>	map(Function<? super T,? extends U> function)	Composite function to convert a result value to another value.
Result<T>	onFailure(Consumer<? super Throwable> callback)	Passive error handler.
Result<T>	onSuccess(Consumer<? super T> callback)	Passive success handler.
static <E> Result<E>	success(E value)	Creates a successful result.
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

success

@Nonnull
@CheckReturnValue
public static <E> Result<E> success(@Nullable
                                    E value)

Creates a successful result.

Type Parameters:

E - The success type

Parameters:

value - The success value

Returns:

Result

failure

@Nonnull
@CheckReturnValue
public static <E> Result<E> failure(@Nonnull
                                    Throwable error)

Creates a failure result.

Type Parameters:

E - The success type

Parameters:

error - The failure throwable

Returns:

Result

Throws:

IllegalArgumentException - If the provided error is null

defer

@Nonnull
@CheckReturnValue
public static <E> Result<E> defer(@Nonnull
                                  Supplier<? extends E> supplier)

Creates a result instance from the provided supplier.
If the supplier throws an exception, a failure result is returned.

Type Parameters:

E - The success type

Parameters:

supplier - The supplier

Returns:

Result instance with the supplied value or exception failure

Throws:

IllegalArgumentException - If the supplier is null

isFailure

public boolean isFailure()

True if this result is a failure.
Use getFailure() or expect(Predicate) to handle failures.

Returns:

True, if this is a failure result

isSuccess

public boolean isSuccess()

True if this result is a success.
Use get() or map(Function) to handle success values.

Returns:

True, if this is a successful result

onFailure

@Nonnull
public Result<T> onFailure(@Nonnull
                           Consumer<? super Throwable> callback)

Passive error handler.
This will apply the provided callback if isFailure() is true and return the same result for further chaining.

Parameters:

callback - The passive callback

Returns:

The same result instance

Throws:

IllegalArgumentException - If the callback is null

onSuccess

@Nonnull
public Result<T> onSuccess(@Nonnull
                           Consumer<? super T> callback)

Passive success handler.
This will apply the provided callback if isSuccess() is true and return the same result for further chaining.

Parameters:

callback - The passive callback

Returns:

The same result instance

Throws:

IllegalArgumentException - If the callback is null

map

@Nonnull
@CheckReturnValue
public <U> Result<U> map(@Nonnull
                         Function<? super T,? extends U> function)

Composite function to convert a result value to another value.
This will only apply the function is isSuccess() is true.

Type Parameters:

U - The result type

Parameters:

function - The conversion function

Returns:

The mapped result

Throws:

IllegalArgumentException - If the provided function is null

See Also:

flatMap(Function)

flatMap

@Nonnull
@CheckReturnValue
public <U> Result<U> flatMap(@Nonnull
                             Function<? super T,? extends Result<U>> function)

Composite function to convert a result value to another result.
This will only apply the function is isSuccess() is true.

Type Parameters:

U - The result type

Parameters:

function - The conversion function

Returns:

The mapped result

Throws:

IllegalArgumentException - If the provided function is null

get

public T get()

Unwraps the success value of this result.
This only works if isSuccess() is true and throws otherwise.

Returns:

The result value

Throws:

IllegalStateException - If the result is not successful

getFailure

@Nullable
public Throwable getFailure()

Unwraps the error for this result.
This will be null if isFailure() is false.

Returns:

The error or null

expect

@Nonnull
public Result<T> expect(@Nonnull
                        Predicate<? super Throwable> predicate)

Throws the wrapped exception if the provided predicate returns true.
This will never provide a null error to the predicate. A successful result will never throw.

Parameters:

predicate - The test predicate

Returns:

The same result instance

Throws:

IllegalArgumentException - If the provided predicate is null

IllegalStateException - If the predicate returns true, the cause will be the wrapped exception

toString

public String toString()

Overrides:

toString in class Object