org.checkerframework.checker.nullness.util

Class Opt

java.lang.Object

org.checkerframework.checker.nullness.util.Opt

@AnnotatedFor(value="nullness")
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.util.Opt.orElse;

or

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

Runtime Dependency: If you use this class, you must distribute (or link to) checker-qual.jar, along with your binaries. Or, you can 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.

Type Parameters:

T - the type of the argument

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, throw an exception to be created by the provided supplier.

Throws:

X extends Throwable

See Also:

Optional.orElseThrow(Supplier)