Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;

import java.util.Map;
import java.util.function.Function;

public class Main {
    public static <K, V> Map<K, Collection<V>> toMap(final Collection<? extends V> items,
            final Function<V, K> mapper) {
        Map<K, Collection<V>> buffer = new HashMap<K, Collection<V>>();
        // TODO this isn't probably thread-safe
        items.stream().forEach(item -> {
            K key = mapper.apply(item);
            Collection<V> c = buffer.getOrDefault(key, new ArrayList<V>());
            c.add(item);
            buffer.put(key, c);
        });
        return buffer;
    }
}