org.apache.calcite.linq4j

Class Nullness

java.lang.Object

org.apache.calcite.linq4j.Nullness

public class Nullness
extends Object

The methods in this class allow to cast nullable reference to a non-nullable one. This is an internal class, and it is not meant to be used as a public API.

The class enables to remove checker-qual runtime dependency, and helps IDEs to see the resulting types of castNonNull better

Method Summary

Modifier and Type	Method and Description
static <T> T	castNonNull(T ref) Enables to threat nullable type as non-nullable with no assertions.

Methods inherited from class java.lang.Object

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

Method Detail

castNonNull

@Pure
 @EnsuresNonNull(value="#1")
public static <T> T castNonNull(T ref)

Enables to threat nullable type as non-nullable with no assertions.

It is useful in the case you have a nullable lately-initialized field like the following: class Wrapper<T> { @Nullable T value; }. That signature allows to use Wrapper with both nullable or non-nullable types: Wrapper<@Nullable Integer> vs Wrapper<Integer>. Suppose you need to implement T get() { return value; } The issue is checkerframework does not permit that because T has unknown nullability, so the following needs to be used: T get() { return sneakyNull(value); }

Type Parameters:

T - the type of the reference

Parameters:

ref - a reference of @Nullable type, that is non-null at run time

Returns:

the argument, casted to have the type qualifier @NonNull