net.dongliu.commons.collection.Maps Maven / Gradle / Ivy
package net.dongliu.commons.collection;
import javax.annotation.Nullable;
import java.util.*;
import java.util.function.Function;
/**
* Utils method for map
*
* @author Liu Dong
*/
public class Maps {
/**
* If map is null, return immutable empty map; else return self
*/
public static Map nullToEmpty(@Nullable Map map) {
return map == null ? Maps.of() : map;
}
/**
* Create immutable view of this Set.
*/
public static Map wrapImmutable(Map map) {
return Collections.unmodifiableMap(map);
}
/**
* Create a immutable map with content
*/
public static Map copyImmutable(Map map) {
return Collections.unmodifiableMap(new HashMap<>(map));
}
/**
* Convert map value, return new map
*/
public static Map convert(Map map, Function function) {
Map newMap = Maps.create();
map.forEach((k, v) -> newMap.put(k, function.apply(v)));
return newMap;
}
/**
* Create mutable empty map
*/
public static Map create() {
return new HashMap<>();
}
/**
* create mutable map
*/
public static Map create(K key, V value) {
Map map = new HashMap<>();
map.put(key, value);
return map;
}
/**
* create mutable map
*/
public static Map create(K key1, V value1, K key2, V value2) {
Map map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
return map;
}
/**
* create mutable map
*/
public static Map create(K key1, V value1, K key2, V value2,
K key3, V value3) {
Map map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
map.put(key3, value3);
return map;
}
/**
* create mutable map
*/
public static Map create(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4) {
Map map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
map.put(key3, value3);
map.put(key4, value4);
return map;
}
/**
* create mutable map
*/
public static Map create(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4,
K key5, V value5) {
Map map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
map.put(key3, value3);
map.put(key4, value4);
map.put(key5, value5);
return map;
}
/**
* create mutable map
*/
public static Map create(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4,
K key5, V value5, K key6, V value6) {
Map map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
map.put(key3, value3);
map.put(key4, value4);
map.put(key5, value5);
map.put(key6, value6);
return map;
}
/**
* create mutable map
*/
public static Map create(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4,
K key5, V value5, K key6, V value6,
K key7, V value7) {
Map map = new HashMap<>();
map.put(key1, value1);
map.put(key2, value2);
map.put(key3, value3);
map.put(key4, value4);
map.put(key5, value5);
map.put(key6, value6);
map.put(key7, value7);
return map;
}
/**
* Create immutable empty map
*/
public static Map of() {
return Collections.emptyMap();
}
/**
* create immutable map
*/
public static Map of(K key, V value) {
return Collections.singletonMap(key, value);
}
/**
* create immutable map
*/
public static Map of(K key1, V value1, K key2, V value2) {
return wrapImmutable(create(key1, value1, key2, value2));
}
/**
* create immutable map
*/
public static Map of(K key1, V value1, K key2, V value2,
K key3, V value3) {
return wrapImmutable(create(key1, value1, key2, value2, key3, value3));
}
/**
* create immutable map
*/
public static Map of(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4) {
return wrapImmutable(create(key1, value1, key2, value2, key3, value3, key4, value4));
}
/**
* create immutable map
*/
public static Map of(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4,
K key5, V value5) {
return wrapImmutable(create(key1, value1, key2, value2, key3, value3, key4, value4, key5, value5));
}
/**
* create immutable map
*/
public static Map of(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4,
K key5, V value5, K key6, V value6) {
return wrapImmutable(create(key1, value1, key2, value2, key3, value3, key4, value4, key5, value5, key6, value6));
}
/**
* create immutable map
*/
public static Map of(K key1, V value1, K key2, V value2,
K key3, V value3, K key4, V value4,
K key5, V value5, K key6, V value6,
K key7, V value7) {
return wrapImmutable(create(key1, value1, key2, value2, key3, value3, key4, value4, key5, value5, key6, value6,
key7, value7));
}
/**
* Combine two list to map
*/
public static Map zip(List keys, List values) {
if (keys.size() != values.size()) {
throw new IllegalArgumentException("Key and value size not equals");
}
Map map = new HashMap<>();
Iterator keyIter = keys.iterator();
Iterator valueIter = values.iterator();
while (keyIter.hasNext() && valueIter.hasNext()) {
map.put(keyIter.next(), valueIter.next());
}
return map;
}
@SafeVarargs
public static Map createFrom(Pair... values) {
Map map = new HashMap<>();
for (Pair tuple : values) map.put(tuple.first(), tuple.second());
return map;
}
public static Map createFrom(Collection> values) {
Map map = new HashMap<>();
for (Pair tuple : values) map.put(tuple.first(), tuple.second());
return map;
}
@SafeVarargs
public static Map from(Pair... values) {
if (values.length == 0) {
return of();
}
return wrapImmutable(createFrom(values));
}
public static Map from(Collection> values) {
return wrapImmutable(createFrom(values));
}
}
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