Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
import java.lang.reflect.Method;

import java.util.Collection;
import java.util.HashMap;

import java.util.Map;

public class Main {
    /**
     * Creates a map with the elements of the collection as values using the
     * specified keyMethod to obtain the key from the elements.
     */
    @SuppressWarnings("unchecked")
    public static <K, T> Map<K, T> createMap(Collection<T> collection, String keyMethod) {
        Map<K, T> map = new HashMap<>(collection.size());

        if (collection.isEmpty()) {
            return map;
        }

        Class<?> elementClass = collection.iterator().next().getClass();

        Method getKeyMethod;

        try {
            getKeyMethod = elementClass.getMethod(keyMethod, new Class[0]);
        } catch (Exception e) {
            throw new RuntimeException("Failed to get key method", e);
        }

        for (T element : collection) {
            K key;
            try {
                key = (K) getKeyMethod.invoke(element, (Object[]) null);
            } catch (Exception e) {
                throw new RuntimeException("Failed to get key", e);
            }

            map.put(key, element);
        }

        return map;
    }
}