org.checkerframework.checker.nullness

Class Opt

java.lang.Object

org.checkerframework.checker.nullness.Opt

public final class Opt
extends Object

Utility class for the Nullness Checker, providing every method in Optional, but written for possibly-null references rather than for the Optional type.

To avoid the need to write the Opt class name at invocation sites, do:

import static org.checkerframework.checker.nullness.Opt.orElse;

or

import static org.checkerframework.checker.nullness.Opt.*;

Runtime Dependency

Please note that using this class introduces a runtime dependency. This means that you need to distribute (or link to) the Checker Framework, along with your binaries.

To eliminate this dependency, you can simply copy this class into your own project.

See Also:

Optional

Method Summary

Modifier and Type	Method and Description
static <T> T	filter(T primary, Predicate<? super T> predicate) If primary is non-null, and its value matches the given predicate, return the value.
static <T> T	get(T primary) If primary is non-null, returns it, otherwise throws NoSuchElementException.
static <T> void	ifPresent(T primary, Consumer<? super T> consumer) If primary is non-null, invoke the specified consumer with the value, otherwise do nothing.
static boolean	isPresent(@Nullable Object primary) Returns true if primary is non-null, false if primary is null.
static <T,U> U	map(T primary, Function<? super T,? extends U> mapper) If primary is non-null, apply the provided mapping function to it and return the result.
static <T> T	orElse(T primary, T other) Return primary if it is non-null.
static <T> T	orElseGet(T primary, Supplier<? extends T> other) Return primary if it is non-null.
static <T,X extends Throwable> T	orElseThrow(T primary, Supplier<? extends X> exceptionSupplier) Return primary if it is non-null.

Methods inherited from class java.lang.Object

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

Method Detail

get

public static <T> T get(T primary)

If primary is non-null, returns it, otherwise throws NoSuchElementException.

Parameters:

primary - a non-null value to return

Returns:

primary if it is non-null

Throws:

NoSuchElementException - if primary is null

See Also:

Optional.get()

isPresent

@EnsuresNonNullIf(expression="#1",
                  result=true)
public static boolean isPresent(@Nullable Object primary)

Returns true if primary is non-null, false if primary is null.

See Also:

Optional.isPresent()

ifPresent

public static <T> void ifPresent(T primary,
                                 Consumer<? super T> consumer)

If primary is non-null, invoke the specified consumer with the value, otherwise do nothing.

See Also:

Optional.ifPresent(Consumer)

filter

public static <T> T filter(T primary,
                           Predicate<? super T> predicate)

If primary is non-null, and its value matches the given predicate, return the value. If primary is null or its non-null value does not match the predicate, return null.

See Also:

Optional.filter(Predicate)

map

public static <T,U> U map(T primary,
                          Function<? super T,? extends U> mapper)

If primary is non-null, apply the provided mapping function to it and return the result. If primary is null, return null.

See Also:

Optional.map(Function)

orElse

public static <T> T orElse(T primary,
                           T other)

Return primary if it is non-null. If primary is null, return other.

See Also:

Optional.orElse(Object)

orElseGet

public static <T> T orElseGet(T primary,
                              Supplier<? extends T> other)

Return primary if it is non-null. If primary is null, invoke other and return the result of that invocation.

See Also:

Optional.orElseGet(Supplier)

orElseThrow

public static <T,X extends Throwable> T orElseThrow(T primary,
                                                    Supplier<? extends X> exceptionSupplier)
                                             throws X extends Throwable

Return primary if it is non-null. If primary is null, return an exception to be created by the provided supplier.

Throws:

X extends Throwable

See Also:

Optional.orElseThrow(Supplier)