Main Class File:

package me.scherer.Zach;
import java.util.logging.Logger;

import org.bukkit.plugin.PluginManager;
import org.bukkit.plugin.java.JavaPlugin;

public class Zach extends JavaPlugin  {

    private final ZachBlockListener playerListener = new ZachBlockListener(this);
    Logger log = Logger.getLogger("Minecraft");
    public void onEnable(){
        log.info("Your plugin has been enabled.");
        PluginManager pm = this.getServer().getPluginManager();}
        pm.registerEvent(Event.Type.BLOCK_BREAK, blockListener, Event.Priority.Normal, this);
    }
    public void onDisable(){
        log.info("Plugin Disabled!");
    }
}
Block Listener Class File:
package me.scherer.Zach;

import org.bukkit.event.block.BlockBreakEvent;
import org.bukkit.event.block.BlockListener;

public class ZachBlockListener {

}public class ZachBlockListener extends BlockListener{ //Code here }
 public Zach plugin;}

public void onBlockBreak(BlockBreakEvent event){
     Block block = event.getBlock();
     if(block.equals(Material.LEAVES)}
          {if(Math.random() * 100 <= 50){ // 50 percent chance of it happening
               ItemStack is= new ItemStack(Material.APPLE,2)
               block.getWorld().dropItemNaturally(block.getLocation, is);}