org.httprpc.kilo.util.Optionals Maven / Gradle / Ivy
/*
* 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 org.httprpc.kilo.util;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* Provides static utility methods for working with optional values.
*/
public class Optionals {
private Optionals() {
}
/**
* Returns the first non-{@code null} argument value.
*
* @param
* The argument type.
*
* @param values
* The argument values.
*
* @return
* The first non-{@code null} argument value, or {@code null} if only
* {@code null} values were provided.
*/
@SafeVarargs
public static T coalesce(T... values) {
for (var i = 0; i < values.length; i++) {
var value = values[i];
if (value != null) {
return value;
}
}
return null;
}
/**
* Applies a mapping function to an optional value.
*
* @param
* The value type.
*
* @param
* The type produced by the mapping function.
*
* @param value
* The optional value.
*
* @param transform
* The mapping function to apply.
*
* @return
* The result of applying the mapping function to the provided value, or
* {@code null} if the value was {@code null}.
*/
public static U map(T value, Function transform) {
if (transform == null) {
throw new IllegalArgumentException();
}
return (value == null) ? null : transform.apply(value);
}
/**
* Performs an action on an optional value.
*
* @param
* The value type.
*
* @param value
* The optional value.
*
* @param action
* The action to perform if the provided value is not {@code null}.
*/
public static void perform(T value, Consumer action) {
if (action == null) {
throw new IllegalArgumentException();
}
if (value != null) {
action.accept(value);
}
}
}