javascalautils.Success Maven / Gradle / Ivy
/**
* Copyright 2015 Peter Nerg
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of the License at
*
*
http://www.apache.org/licenses/LICENSE-2.0
*
*
Unless required by applicable law or agreed to in writing, software distributed under the
* License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing permissions and
* limitations under the License.
*/
package javascalautils;
import java.io.Serializable;
import java.util.NoSuchElementException;
import java.util.function.Predicate;
import java.util.function.Supplier;
import static javascalautils.TryCompanion.Try;
/**
* Represents the successful implementation of {@link Try}.
* Acts as a carrier for the result of a successful computation.
* For examples on usage refer to the documentation for {@link Try}.
*
* @author Peter Nerg
* @since 1.0
* @param The type of the value represented by this instance
*/
public final class Success extends SingleItemContainer implements Try, Serializable {
private static final long serialVersionUID = -5588727176438040926L;
private final T value;
/**
* Creates a 'successful' instance with the provided value.
* Null values are allowed.
*
* @param value The value represented by this instance
* @since 1.0
*/
public Success(T value) {
this.value = value;
}
/**
* Always returns true.
*
* @since 1.0
*/
@Override
public boolean isSuccess() {
return true;
}
/**
* Returns the value provided in the constructor.
* I.e. the provided supplier is never use.
*
* @since 1.0
*/
@Override
public T getOrElse(Supplier supplier) {
return value;
}
/**
* Always returns this.
* I.e. the provided supplier is never use.
*
* @since 1.0
*/
@Override
public Try orElse(Supplier> supplier) {
return this;
}
/**
* Returns the value held by this instance.
* Never throws an exception as this is a success
*
* @since 1.0
*/
@Override
public T get() {
return value;
}
/**
* Returns a {@link Failure} with an {@link UnsupportedOperationException}.
* Since this is a success there is no failure to map to a success i.e. this
* is a illegal operation.
*
* @since 1.0
*/
@Override
public Try failed() {
return new Failure<>(new UnsupportedOperationException("Cannot make a Failure of a Success"));
}
/**
* Applies the value to the function and returns the {@link Try} representing the mapped value.
*
* @since 1.0
*/
@Override
public Try map(ThrowableFunction1 function) {
return Try(() -> function.apply(value));
}
/**
* Applies the value to the function and returns the {@link Try} generated by the function.
*
* @since 1.2
*/
@Override
public Try flatMap(ThrowableFunction1> function) {
try {
return function.apply(value);
} catch (Throwable t) {
return new Failure<>(t);
}
}
/**
* Applies the predicate to the value of this instance, if it matches this is returned else
* a {@link Failure}.
*
* @since 1.4
*/
@Override
public Try filter(Predicate predicate) {
return predicate.test(value)
? this
: new Failure<>(
new NoSuchElementException("Predicate did not match value, now empty result"));
}
/**
* Always returns this .
* As per definition this is a success and will not need to be recovered.
*
* @since 1.4
*/
@Override
public Try recover(ThrowableFunction1 function) {
return this;
}
/**
* Always returns this .
* As per definition this is a success and will not need to be recovered.
*
* @since 1.4
*/
@Override
public Try recoverWith(ThrowableFunction1> function) {
return this;
}
/**
* Returns a String representation of the instance.
*
* @since 1.0
*/
@Override
public String toString() {
return String.format("Success(%s)", value != null ? value.toString() : "NULL VALUE");
}
}