org.hamcrest

Interface Matcher<T>

All Superinterfaces:

SelfDescribing

All Known Implementing Classes:

AllOf, AnyOf, ArrayAsIterableMatcher, BaseMatcher, BigDecimalCloseTo, CharSequenceLength, CombinableMatcher, CustomMatcher, CustomTypeSafeMatcher, DescribedAs, DiagnosingMatcher, Every, FeatureMatcher, HasEqualValues, HasItemInArray, HasProperty, HasPropertyWithValue, HasToString, HasXPath, Is, IsAnything, IsArray, IsArrayContainingInAnyOrder, IsArrayContainingInOrder, IsArrayWithSize, IsBlankString, IsCloseTo, IsCollectionContaining, IsCollectionWithSize, IsCompatibleType, IsEmptyCollection, IsEmptyIterable, IsEmptyString, IsEqual, IsEqualCompressingWhiteSpace, IsEqualIgnoringCase, IsEventFrom, IsIn, IsInstanceOf, IsIterableContaining, IsIterableContainingInAnyOrder, IsIterableContainingInOrder, IsIterableContainingInRelativeOrder, IsIterableWithSize, IsMapContaining, IsMapWithSize, IsNaN, IsNot, IsNull, IsSame, MatchesPattern, SamePropertyValuesAs, StringContains, StringContainsInOrder, StringEndsWith, StringRegularExpression, StringStartsWith, SubstringMatcher, TypeSafeDiagnosingMatcher, TypeSafeMatcher

public interface Matcher<T>
extends SelfDescribing

A matcher over acceptable values. A matcher is able to describe itself to give feedback when it fails.

Matcher implementations should NOT directly implement this interface. Instead, extend the BaseMatcher abstract class, which will ensure that the Matcher API can grow to support new features and remain compatible with all Matcher implementations.

When using Hamcrest, there is no guarantee as to how often matches() or describeMismatch() will be called, so the objects passed as actual arguments should not change when referenced. If you're testing a stream, a good practice is to collect the contents of the stream before matching.

N.B. Well designed matchers should be immutable.

See Also:

BaseMatcher

Method Summary

Modifier and Type	Method and Description
void	_dont_implement_Matcher___instead_extend_BaseMatcher_() Deprecated. to make
void	describeMismatch(java.lang.Object actual, Description mismatchDescription) Generate a description of why the matcher has not accepted the item.
boolean	matches(java.lang.Object actual) Evaluates the matcher for argument item.

Methods inherited from interface org.hamcrest.SelfDescribing

describeTo

Method Detail

matches

boolean matches(java.lang.Object actual)

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:

actual - the object against which the matcher is evaluated.

Returns:

true if item matches, otherwise false.

See Also:

BaseMatcher

describeMismatch

void describeMismatch(java.lang.Object actual,
                      Description mismatchDescription)

Generate a description of why the matcher has not accepted the item. The description will be part of a larger description of why a matching failed, so it should be concise. This method assumes that matches(item) is false, but will not check this.

Parameters:

actual - The item that the Matcher has rejected.

mismatchDescription - The description to be built or appended to.

_dont_implement_Matcher___instead_extend_BaseMatcher_

@Deprecated
void _dont_implement_Matcher___instead_extend_BaseMatcher_()

Deprecated. to make

This method simply acts a friendly reminder not to implement Matcher directly and instead extend BaseMatcher. It's easy to ignore JavaDoc, but a bit harder to ignore compile errors .

See Also:

for reasons why., BaseMatcher