com.blacklocus.misc.NoNullsMap.java Source code

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Here is the source code for com.blacklocus.misc.NoNullsMap.java

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/**
 * Copyright 2013 BlackLocus
 *
 * 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 com.blacklocus.misc;

import com.google.common.collect.ImmutableMap;

import java.util.HashMap;

/**
 * A map that ignores null keys or values. The key won't be added at all if it is null or its value is null.
 * Only applies to {@link #put(Object, Object)}.
 * <p>
 * Use {@link #of(Object, Object)}... as a transparent replacement of {@link ImmutableMap#of()} where nulls are
 * possible, because ImmutableMap will not accept null values anyways.
 */
public class NoNullsMap<K, V> extends HashMap<K, V> {

    public static <K, V> ImmutableMap<K, V> of(K k1, V v1) {
        NoNullsMap<K, V> map = new NoNullsMap<K, V>(1);
        map.put(k1, v1);
        return ImmutableMap.copyOf(map);

    }

    public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
        NoNullsMap<K, V> map = new NoNullsMap<K, V>(3);
        map.put(k1, v1);
        map.put(k2, v2);
        map.put(k3, v3);
        return ImmutableMap.copyOf(map);
    }

    public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
        NoNullsMap<K, V> map = new NoNullsMap<K, V>(3);
        map.put(k1, v1);
        map.put(k2, v2);
        map.put(k3, v3);
        map.put(k4, v4);
        return ImmutableMap.copyOf(map);
    }

    public static <K, V> ImmutableMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
        NoNullsMap<K, V> map = new NoNullsMap<K, V>(3);
        map.put(k1, v1);
        map.put(k2, v2);
        map.put(k3, v3);
        map.put(k4, v4);
        map.put(k5, v5);
        return ImmutableMap.copyOf(map);
    }

    private NoNullsMap(int initialCapacity) {
        super(initialCapacity);
    }

    /**
     * Ignores null keys or values. The key won't be added at all if it is null or its value is null.
     */
    @Override
    public V put(K key, V value) {
        return key != null && value != null ? super.put(key, value) : null;
    }
}