notNullValue

notNullValue is a matcher in the Hamcrest library used for unit testing in Java. It represents the concept of a value that is not null and is commonly used in assertions to ensure that a given expression produces a non-null result.

There are two forms of the matcher. notNullValue() matches any non-null value, while notNullValue(Class<T> type) matches a non-null value that is also of the specified type. The type variant helps enforce both non-nullness and a expected type, providing stronger assertions in typed tests.

Typical usage involves static imports from Hamcrest’s core matchers and assertion utilities, for example:

import static org.hamcrest.CoreMatchers.notNullValue;

import static org.hamcrest.MatcherAssert.assertThat;

assertThat(foo, notNullValue());

assertThat(bar, notNullValue(String.class));

In these examples, the assertion passes if foo is not null, and bar is not null and is an instance of String. notNullValue is part of Hamcrest’s core matchers and is a basic tool for null-safety checks. It is often used in combination with other matchers to express more complex expectations about values, such as ensuring a value is non-null before performing further validations.

See also: null value concepts, other Hamcrest matchers such as is, not, and type-safe matchers that help build expressive assertions.