BlockRegen

package me.pogostick29dev.blockregen;

import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.block.Block;
import org.bukkit.block.BlockState;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityExplodeEvent;
import org.bukkit.plugin.java.JavaPlugin;

public class BlockRegen extends JavaPlugin implements Listener {

    public void onEnable() {
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
    }

    @EventHandler
    public void onEntityExplode(EntityExplodeEvent e) {
        for (Block b : e.blockList()) {
            final BlockState state = b.getState();

            b.setType(Material.AIR); // Stop item drops from spawning.

            int delay = 20;

            if ((b.getType() == Material.SAND) || (b.getType() == Material.GRAVEL)) {
                delay += 1;
            }

            Bukkit.getServer().getScheduler().scheduleSyncDelayedTask(this, new Runnable() {
                public void run() {
                    state.update(true, false);
                }
            }, delay);
        }
    }
}