com.getperka.flatpack.util.FlatPackCollections Maven / Gradle / Ivy
/*
* #%L
* FlatPack serialization code
* %%
* Copyright (C) 2012 Perka Inc.
* %%
* 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.
* #L%
*/
package com.getperka.flatpack.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* A class with factory methods that vend different types of collections based on intended use.
* These methods exist to help ensure that code will operate with predictable iteration order where
* iteration is required.
*/
public class FlatPackCollections {
/**
* Returns the default List implementation to use.
*/
public static List listForAny() {
return new ArrayList();
}
/**
* Returns a Map with stable iteration order.
*/
public static Map mapForIteration() {
return new LinkedHashMap();
}
/**
* Returns a Map whose {@link Iterable} methods throw {@link UnsupportedOperationException}.
*/
@SuppressWarnings("serial")
public static Map mapForLookup() {
return new HashMap() {
@Override
public Set> entrySet() {
throw new UnsupportedOperationException();
}
@Override
public Set keySet() {
throw new UnsupportedOperationException();
}
@Override
public Collection values() {
throw new UnsupportedOperationException();
}
};
}
/**
* Returns a Set guaranteed to have stable iteration order.
*/
public static Set setForIteration() {
return new LinkedHashSet();
}
/**
* Returns a Set that cannot be iterated over.
*/
@SuppressWarnings("serial")
public static Set setForLookup() {
return new HashSet() {
@Override
public Iterator iterator() {
throw new UnsupportedOperationException();
}
};
}
public static , V> SortedMap sortedMapForIteration() {
return new TreeMap();
}
private FlatPackCollections() {}
}