org.hamcrest.core
Class IsNull<T>

java.lang.Object
  extended by org.hamcrest.BaseMatcher<T>
      extended by org.hamcrest.core.IsNull<T>
All Implemented Interfaces:
Matcher<T>, SelfDescribing

public class IsNull<T>
extends BaseMatcher<T>

Is the value null?


Constructor Summary
IsNull()
           
 
Method Summary
 void describeTo(Description description)
          Generates a description of the object.
 boolean matches(Object o)
          Evaluates the matcher for argument item.
static Matcher<Object> notNullValue()
          A shortcut to the frequently used not(nullValue()).
static
<T> Matcher<T>
notNullValue(Class<T> type)
          A shortcut to the frequently used not(nullValue(X.class)).
static Matcher<Object> nullValue()
          Creates a matcher that matches if examined object is null.
static
<T> Matcher<T>
nullValue(Class<T> type)
          Creates a matcher that matches if examined object is null.
 
Methods inherited from class org.hamcrest.BaseMatcher
_dont_implement_Matcher___instead_extend_BaseMatcher_, describeMismatch, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

IsNull

public IsNull()
Method Detail

matches

public boolean matches(Object o)
Description copied from interface: Matcher
Evaluates the matcher for argument item.

This method matches against Object, instead of the generic type T. This is because the caller of the Matcher does not know at runtime what the type is (because of type erasure with Java generics). It is down to the implementations to check the correct type.

Parameters:
o - the object against which the matcher is evaluated.
Returns:
true if item matches, otherwise false.
See Also:
BaseMatcher

describeTo

public void describeTo(Description description)
Description copied from interface: SelfDescribing
Generates a description of the object. The description may be part of a a description of a larger object of which this is just a component, so it should be worded appropriately.

Parameters:
description - The description to be built or appended to.

nullValue

public static Matcher<Object> nullValue()
Creates a matcher that matches if examined object is null.

For example:

assertThat(cheese, is(nullValue())


notNullValue

public static Matcher<Object> notNullValue()
A shortcut to the frequently used not(nullValue()).

For example:

assertThat(cheese, is(notNullValue()))
instead of:
assertThat(cheese, is(not(nullValue())))


nullValue

public static <T> Matcher<T> nullValue(Class<T> type)
Creates a matcher that matches if examined object is null. Accepts a single dummy argument to facilitate type inference.

For example:

assertThat(cheese, is(nullValue(Cheese.class))

Parameters:
type - dummy parameter used to infer the generic type of the returned matcher

notNullValue

public static <T> Matcher<T> notNullValue(Class<T> type)
A shortcut to the frequently used not(nullValue(X.class)). Accepts a single dummy argument to facilitate type inference..

For example:

assertThat(cheese, is(notNullValue(X.class)))
instead of:
assertThat(cheese, is(not(nullValue(X.class))))

Parameters:
type - dummy parameter used to infer the generic type of the returned matcher


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