EntityUtil.java

import org.bukkit.Location;
import org.bukkit.World;
import org.bukkit.entity.Entity;
import org.bukkit.entity.Player;

import java.util.*;
import java.util.stream.Collectors;

/**
 * Created by LynxPlay on 28.10.2016.
 */
public class EntityUtil {

    /**
     * @param locations         The locations which will be used as the center
     * @param radius      The max. radius in which the entiys must be (from the center)
     * @param entityClass The class of the entiys. Used to filter the list. Entiy will
     * @param <T>
     * @return A list of entities extending T
     */
    public static <T extends Entity> List<T> getNearbyEntitys(final double radius, final Class<T> entityClass, Collection<Location> locations) {
        if (locations.isEmpty()) return new ArrayList<>();

        return locations.stream().findAny().get().getWorld().getEntitiesByClass(entityClass).stream()
                .filter(entity -> isNearby(entity, radius, locations))
                .map(t -> entityClass.cast(t))
                .collect(Collectors.toList());
    }

    public static <T extends Entity> List<T> getNearbyEntitys(final double radius, final Class<T> entityClass, Location... locations) {
        return getNearbyEntitys(radius , entityClass , Arrays.asList(locations));
    }

    /**
     *
     * @param world the world the entity is in
     * @param uuid the entitys uuid
     * @param entityClass the entitys class
     * @return the entity and if not found null
     */
    public static <T extends Entity> T getFrom(World world , UUID uuid , Class<T> entityClass) {
        return world.getEntitiesByClass(entityClass).stream().filter(e -> e != null && e.getUniqueId().equals(uuid)).findFirst().orElse(null);
    }

    /**
     * @param player The player to check
     * @return Whether the player is a real player or just a npc
     */
    public static boolean isRealPlayer(Player player) {
        return player.getAddress() != null;
    }

    /**
     * @param player The player to heal
     * @param amount The health to heal
     */
    public static void heal(Player player, int amount) {
        player.setHealth(Math.min(player.getHealth() + amount, player.getMaxHealth()));
    }

    private static boolean isNearby(Entity entity, final double radius, Collection<Location> locations) {
        return locations.stream().filter(location -> location.distance(entity.getLocation()) <= radius).findAny().isPresent();
    }
}