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Grace Framework : Grace Util
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/*
* Copyright 2011-2022 the original author or authors.
*
* 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
*
* https://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 grails.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Collection utility methods.
*
* @author Burt Beckwith
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public final class CollectionUtils {
private CollectionUtils() {
// static only
}
public static Map newMap(Object... keysAndValues) {
if (keysAndValues == null) {
return Collections.emptyMap();
}
if (keysAndValues.length % 2 == 1) {
throw new IllegalArgumentException("Must have an even number of keys and values");
}
Map map = new HashMap<>();
for (int i = 0; i < keysAndValues.length; i += 2) {
map.put((K) keysAndValues[i], (V) keysAndValues[i + 1]);
}
return map;
}
public static Set newSet(T... values) {
if (values == null) {
return Collections.emptySet();
}
return new HashSet<>(Arrays.asList(values));
}
public static List newList(T... values) {
if (values == null) {
return Collections.emptyList();
}
return new ArrayList<>(Arrays.asList(values));
}
/**
* Gets a child map of the given parent map or returns an empty map if it doesn't exist
*
* @param parent The parent map
* @param key The key that holds the child map
* @return The child map
*/
public static Map getOrCreateChildMap(Map parent, String key) {
Object o = parent.get(key);
if (o instanceof Map) {
return (Map) o;
}
return new LinkedHashMap();
}
}