com.codingopus.guava.custom.collectors.ImmutableMapCollector.java Source code

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Here is the source code for com.codingopus.guava.custom.collectors.ImmutableMapCollector.java

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/*
 * Copyright 2016 Bharat Savani
 *
 *  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.codingopus.guava.custom.collectors;

import java.util.function.Function;
import java.util.stream.Collector;

import com.google.common.collect.ImmutableMap;

public final class ImmutableMapCollector<T, K, V> {

    public static <T, K> Collector<T, ?, ImmutableMap<K, T>> toImmutableMap(
            final Function<? super T, ? extends K> keyExtractor) {

        return toImmutableMap(keyExtractor, Function.identity());
    }

    public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
            final Function<? super T, ? extends K> keyExtractor,
            final Function<? super T, ? extends V> valueExtractor) {

        return Collector.of(ImmutableMap::builder,
                (map, val) -> map.put(keyExtractor.apply(val), valueExtractor.apply(val)),
                (left, right) -> left.putAll(right.build()), ImmutableMap.Builder<K, V>::build);
    }

}