com.cedarsoftware.util.MapUtilities Maven / Gradle / Ivy
package com.cedarsoftware.util;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
/**
* Usefule utilities for Maps
*
* @author Kenneth Partlow
* @author John DeRegnaucourt
*
* Copyright (c) Cedar Software LLC
*
* 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
*
* License
*
* 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.
*/
public class MapUtilities
{
/**
* Constructor is declared private since all methods are static.
*/
private MapUtilities()
{
}
/**
* Retrieves a value from a map by key
*
* @param map Map to retrieve item from
* @param key the key whose associated value is to be returned
* @param def value to return if item was not found.
* @return Returns a string value that was found at the location key.
* If the item is null then the def value is sent back.
* If the item is not the expected type, an exception is thrown.
*/
public static T get(Map map, Object key, T def)
{
T val = map.get(key);
return val == null ? def : val;
}
/**
* Retrieves a value from a map by key, if value is not found by the given key throws a 'Throwable.'
* This version allows the value associated to the key to be null, and it still works. In other words,
* if the passed in key is within the map, this method will return whatever is associated to the key, including
* null.
* @param map Map to retrieve item from
* @param key the key whose associated value is to be returned
* @param throwable
* @param Throwable passed in to be thrown *if* the passed in key is not within the passed in map.
* @return the value associated to the passed in key from the passed in map, otherwise throw the passed in exception.
*/
public static Object getOrThrow(Map map, Object key, T throwable) throws T
{
if (map == null)
{
throw new NullPointerException("Map parameter cannot be null");
}
if (throwable == null)
{
throw new NullPointerException("Throwable object cannot be null");
}
if (map.containsKey(key))
{
return map.get(key);
}
throw throwable;
}
/**
* Returns null safe isEmpty check for Map
*
* @param map Map to check, can be null
* @return Returns true if map is empty or null
*/
public static boolean isEmpty(Map map) {
return map == null || map.isEmpty();
}
/**
* Duplicate a map of Set to Class, possibly as unmodifiable
*
* @param other map to duplicate
* @param unmodifiable will the result be unmodifiable
* @return duplicated map
*/
public static Map, Set> dupe(Map, Set> other, boolean unmodifiable) {
final Map, Set> newItemsAssocToClass = new LinkedHashMap<>();
for (Map.Entry, Set> entry : other.entrySet()) {
final Set itemsAssocToClass = new LinkedHashSet<>(entry.getValue());
if (unmodifiable) {
newItemsAssocToClass.computeIfAbsent(entry.getKey(), k -> Collections.unmodifiableSet(itemsAssocToClass));
} else {
newItemsAssocToClass.computeIfAbsent(entry.getKey(), k -> itemsAssocToClass);
}
}
if (unmodifiable) {
return Collections.unmodifiableMap(newItemsAssocToClass);
} else {
return newItemsAssocToClass;
}
}
// Keeping next two methods in case we need to make certain sets unmodifiable still.
public static Map> cloneMapOfSets(final Map> original, final boolean immutable) {
final Map> result = new HashMap<>();
for (Map.Entry> entry : original.entrySet()) {
final T key = entry.getKey();
final Set value = entry.getValue();
final Set clonedSet = immutable
? Collections.unmodifiableSet(value)
: new HashSet<>(value);
result.put(key, clonedSet);
}
return immutable ? Collections.unmodifiableMap(result) : result;
}
public static Map> cloneMapOfMaps(final Map> original, final boolean immutable) {
final Map> result = new LinkedHashMap<>();
for (Map.Entry> entry : original.entrySet()) {
final T key = entry.getKey();
final Map value = entry.getValue();
final Map clonedMap = immutable
? Collections.unmodifiableMap(value)
: new LinkedHashMap<>(value);
result.put(key, clonedMap);
}
return immutable ? Collections.unmodifiableMap(result) : result;
}
/**
* For JDK1.8 support. Remove this and change to Map.of() for JDK11+
*/
public static Map mapOf()
{
return Collections.unmodifiableMap(new LinkedHashMap<>());
}
public static Map mapOf(K k, V v)
{
Map map = new LinkedHashMap<>();
map.put(k, v);
return Collections.unmodifiableMap(map);
}
public static Map mapOf(K k1, V v1, K k2, V v2)
{
Map map = new LinkedHashMap<>();
map.put(k1, v1);
map.put(k2, v2);
return Collections.unmodifiableMap(map);
}
public static Map mapOf(K k1, V v1, K k2, V v2, K k3, V v3)
{
Map map = new LinkedHashMap<>();
map.put(k1, v1);
map.put(k2, v2);
map.put(k3, v3);
return Collections.unmodifiableMap(map);
}
public static Map mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4)
{
Map map = new LinkedHashMap<>();
map.put(k1, v1);
map.put(k2, v2);
map.put(k3, v3);
map.put(k4, v4);
return Collections.unmodifiableMap(map);
}
public static Map mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5)
{
Map map = new LinkedHashMap<>();
map.put(k1, v1);
map.put(k2, v2);
map.put(k3, v3);
map.put(k4, v4);
map.put(k5, v5);
return Collections.unmodifiableMap(map);
}
public static Map mapOf(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6)
{
Map map = new LinkedHashMap<>();
map.put(k1, v1);
map.put(k2, v2);
map.put(k3, v3);
map.put(k4, v4);
map.put(k5, v5);
map.put(k6, v6);
return Collections.unmodifiableMap(map);
}
}
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