Load item names from a file stored inside your plugin.

ItemNames.java

package com.github.jikoo.itemnames;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map.Entry;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.tuple.ImmutablePair;
import org.apache.commons.lang3.tuple.Pair;

import org.bukkit.Bukkit;
import org.bukkit.Material;

import com.google.common.collect.HashMultimap;

/**
 * Load and use a list of items from a file stored in your plugin. Original implementation c/o MasterBugPatch
 * <a href=https://www.spigotmc.org/threads/tutorial-obtaining-actual-item-names.35088/>on Spigot</a>.
 * 
 * @author Jikoo
 */
public class ItemNames {

	private static HashMap<String, String> items;
	private static HashMultimap<String, String> itemsReverse;
	private static final HashMap<Integer, String> potionEffects = new HashMap<>();

	static {
		potionEffects.put(0, "Mundane Potion");
		potionEffects.put(1, "Potion of Regeneration");
		potionEffects.put(2, "Potion of Swiftness");
		potionEffects.put(3, "Potion of Fire Resistance");
		potionEffects.put(4, "Potion of Poison");
		potionEffects.put(5, "Potion of Healing");
		potionEffects.put(6, "Potion of Night Vision");
		potionEffects.put(7, "Clear Potion");
		potionEffects.put(8, "Potion of Weakness");
		potionEffects.put(9, "Potion of Strength");
		potionEffects.put(10, "Potion of Slowness");
		potionEffects.put(11, "Potion of Leaping");
		potionEffects.put(12, "Potion of Harming");
		potionEffects.put(13, "Potion of Water Breathing");
		potionEffects.put(14, "Potion of Invisibility");
		potionEffects.put(15, "Thin Potion");
		potionEffects.put(16, "Awkward Potion");
		potionEffects.put(23, "Bungling Potion");
		potionEffects.put(31, "Debonair Potion");
		potionEffects.put(32, "Thick Potion");
		potionEffects.put(39, "Charming Potion");
		potionEffects.put(47, "Sparkling Potion");
		potionEffects.put(48, "Potent Potion");
		potionEffects.put(55, "Rank Potion");
		potionEffects.put(63, "Stinky Potion");
	}

	private static HashMap<String, String> getItems() {
		if (items != null) {
			return items;
		}
		try (BufferedReader reader = new BufferedReader(new InputStreamReader(
				Bukkit.getPluginManager().getPlugin("Example").getResource("items.tsv")))) {
			items = new HashMap<>();
			itemsReverse = HashMultimap.create();
			String line;
			while ((line = reader.readLine()) != null) {
				line = line.trim();
				if (line.isEmpty()) {
					continue;
				}
				String[] column = line.split("\t");
				String id = column[1] + ":" + column[2];
				items.put(id, column[3]);
				itemsReverse.put(column[3], id);
			}
		} catch (IOException e) {
			throw new RuntimeException("Could not load items from items.tsv!", e);
		}
		return items;
	}

	public static String getMaterialDataName(Material m, short durability) {
		if (m == Material.POTION) {
			return getPotionName(durability);
		} if (m.getMaxDurability() > 0) {
			// Degradable item, find the name of an undamaged one.
			durability = 0;
		}
		String key = m.name() + ":" + durability;
		if (getItems().containsKey(key)) {
			return items.get(key);
		}
		return "Unknown item. Please report this!";
	}

	private static String getPotionName(short durability) {
		StringBuilder potion = new StringBuilder();
		if (((durability >> 6) & 1) == 1) {
			potion.append("Extended ");
		}
		if (((durability >> 14) & 1) == 1) {
			potion.append("Splash ");
		}
		int remainder = durability % 64;
		if (potionEffects.containsKey(remainder)) {
			potion.append(potionEffects.get(remainder));
		} else {
			potion.append(potionEffects.get(remainder % 16));
		}
		if (((durability >> 5) & 1) == 1) {
			potion.append(" II");
		}
		return potion.toString();
	}

	@SuppressWarnings("deprecation")
	public static Pair<Material, Short> matchMaterial(String search) {
		String[] matData = search.split(":");
		if (matData[0].length() < 2) {
			// Too short strings will always result in "air"
			throw new IllegalArgumentException("Search string must be 2 characters minimum.");
		}

		Material material = null;
		Short durability = null;

		if (matData.length > 1) {
			try {
				durability = Short.parseShort(matData[1]);
			} catch (NumberFormatException e) {}
		}

		try {
			material = Material.getMaterial(Integer.parseInt(matData[0]));
			return new ImmutablePair<>(material, durability != null ? durability : 0);
		} catch (NumberFormatException e) {}

		boolean durabilitySet = durability != null;
		if (!durabilitySet) {
			durability = 0;
		}

		int matchLevel = Integer.MAX_VALUE;
		matData[0] = matData[0].replace('_', ' ').toLowerCase();
		for (Entry<String, String> entry : getItems().entrySet()) {
			int current = StringUtils.getLevenshteinDistance(matData[0], entry.getValue().toLowerCase());
			if (current < matchLevel) {
				matchLevel = current;
				String[] entryData = entry.getKey().split(":");
				material = Material.getMaterial(entryData[0]);
				if (!durabilitySet) {
					durability = Short.valueOf(entryData[1]);
				}
			}
			if (current == 0) {
				return new ImmutablePair<>(material, durability);
			}
		}
		// Allow more fuzziness for longer named items
		if (matchLevel < (3 + material.name().length() / 5)) {
			return new ImmutablePair<>(material, durability);
		}
		return null;
	}
}

Items.tsv