gistfile1.java

public class BlockBreaker extends JavaPlugin implements Listener {
    private List<BlockDef> blocks = new ArrayList<BlockDef>();

    public void onEnable() {
        Bukkit.getPluginManager.registerEvents(this);
    
        Bukkit.getScheduler.scheduleSyncRepeatingTask(this, new Runnable() {
            for (BlockDef def : BlockBreaker.this.blocks) {
                if (def.time < System.currentTimeMillis()) {
                    continue;
                }

                def.loc.getWorld().getBlockAt(def.loc).setType(def.mat);
                BlockBreaker.this.blocks.remove(def);
            }
        }, 0L, 20L);
    }

    @EventHandler
    public void onBlockBreak(BlockBreakEvent event) {
        Block block = event.getBlock();
        BlockDef def = new BlockDef(block.getType(), block.getLocation(), System.currentTimeMillis() + (1000 * 10));

        blocks.add(def);
    }

    public static class BlockDef {
        public Material mat;
        public Location loc;
        public long time;

        public BlockDef(Material mat, Location loc, long time) {
            this.mat = mat;
            this.loc = loc;
            this.time = time;
        }
    }
}