org.keycloak.util.EnumWithStableIndex Maven / Gradle / Ivy
/*
* Copyright 2022 Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags.
*
* 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.keycloak.util;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* Classes implementing this interface guarantee that for each instance of this class,
* there exists an mutually unique integer which is stable in time, and identifies
* always the same instance of this class.
* The index might be used for persistence, hence the index of a particular item
* cannot be changed.
* This is mostly usable for @{code enum}s.
*/
public interface EnumWithStableIndex {
/**
* @return Unique numeric index which is stable in time and identifies an instance.
* Reusing the same index for two distinct entries of the same class is forbidden even
* if they cannot exist at the same time (e.g. one is deleted before other is introduced).
*/
public int getStableIndex();
public static Map getReverseIndex(E[] values) {
return Stream.of(values).collect(Collectors.toMap(EnumWithStableIndex::getStableIndex, Function.identity()));
}
}