package org.hamcrest;
import org.hamcrest.internal.ReflectiveTypeFinder;
Convenient base class for Matchers that require a non-null value of a specific type.
This simply implements the null check, checks the type and then casts.
Author: Joe Walnes, Steve Freeman, Nat Pryce
/**
* Convenient base class for Matchers that require a non-null value of a specific type.
* This simply implements the null check, checks the type and then casts.
*
* @author Joe Walnes
* @author Steve Freeman
* @author Nat Pryce
*/
public abstract class TypeSafeMatcher<T> extends BaseMatcher<T> {
private static final ReflectiveTypeFinder TYPE_FINDER = new ReflectiveTypeFinder("matchesSafely", 1, 0);
final private Class<?> expectedType;
The default constructor for simple sub types
/**
* The default constructor for simple sub types
*/
protected TypeSafeMatcher() {
this(TYPE_FINDER);
}
Use this constructor if the subclass that implements matchesSafely
is not the class that binds <T> to a type.
Params: - expectedType – The expectedType of the actual value.
/**
* Use this constructor if the subclass that implements <code>matchesSafely</code>
* is <em>not</em> the class that binds <T> to a type.
* @param expectedType The expectedType of the actual value.
*/
protected TypeSafeMatcher(Class<?> expectedType) {
this.expectedType = expectedType;
}
Use this constructor if the subclass that implements matchesSafely
is not the class that binds <T> to a type.
Params: - typeFinder – A type finder to extract the type
/**
* Use this constructor if the subclass that implements <code>matchesSafely</code>
* is <em>not</em> the class that binds <T> to a type.
* @param typeFinder A type finder to extract the type
*/
protected TypeSafeMatcher(ReflectiveTypeFinder typeFinder) {
this.expectedType = typeFinder.findExpectedType(getClass());
}
Subclasses should implement this. The item will already have been checked for
the specific type and will never be null.
/**
* Subclasses should implement this. The item will already have been checked for
* the specific type and will never be null.
*/
protected abstract boolean matchesSafely(T item);
Subclasses should override this. The item will already have been checked for
the specific type and will never be null.
/**
* Subclasses should override this. The item will already have been checked for
* the specific type and will never be null.
*/
protected void describeMismatchSafely(T item, Description mismatchDescription) {
super.describeMismatch(item, mismatchDescription);
}
Methods made final to prevent accidental override. If you need to override this, there's no point on extending TypeSafeMatcher. Instead, extend the BaseMatcher
. /**
* Methods made final to prevent accidental override.
* If you need to override this, there's no point on extending TypeSafeMatcher.
* Instead, extend the {@link BaseMatcher}.
*/
@Override
@SuppressWarnings({"unchecked"})
public final boolean matches(Object item) {
return item != null
&& expectedType.isInstance(item)
&& matchesSafely((T) item);
}
@SuppressWarnings("unchecked")
@Override
final public void describeMismatch(Object item, Description description) {
if (item == null) {
super.describeMismatch(item, description);
} else if (! expectedType.isInstance(item)) {
description.appendText("was a ")
.appendText(item.getClass().getName())
.appendText(" (")
.appendValue(item)
.appendText(")");
} else {
describeMismatchSafely((T)item, description);
}
}
}