How to place blocks in existing world

[ForgeNewbie]

Hello,

Please forgive the newbie-ness of this question, but I couldn't find the answer anywhere. 

I'm brand new to Minecraft modding. 

 

I want to place blocks in an existing world. 

I think I'm supposed to do something like this: 

 

[embed=425,349]

World world = Minecraft.getMinecraft().theWorld;

world.setBlock(0, 70, 0, Blocks.cactus, 1, 2); //<---java.lang.NullPointerException

[/embed]

 

It seems pretty clear to me that theWorld has not been set to anything yet. 

I think my problem is that I've put this code in my init() method. 

Can anyone tell me where I should put it? 

(Again, I want to place new blocks in an existing world, not a new world). 

 

Much thanks!

 

It probably does not matter, but...

I'm using Forge 1.7.10. 

 

Also, here is the whole code: 

 

[embed=425,349]

package com.example.examplemod;

 

import net.minecraft.client.Minecraft;

import net.minecraft.init.Blocks;

import net.minecraft.server.MinecraftServer;

import net.minecraft.world.World;

import cpw.mods.fml.common.Mod;

import cpw.mods.fml.common.Mod.EventHandler;

import cpw.mods.fml.common.event.FMLInitializationEvent;

 

@Mod(modid = ExampleMod.MODID, version = ExampleMod.VERSION)

public class ExampleMod

{

    public static final String MODID = "examplemod";

    public static final String VERSION = "1.0";

   

    @EventHandler

    public void init(FMLInitializationEvent event)

    {

        World world = Minecraft.getMinecraft().theWorld;

        world.setBlock(0, 70, 0, Blocks.cactus, 1, 2); //<---java.lang.NullPointerException

    }

}

[/embed]

[Anon10W1z]

What....

The world does not exist when you initialize the mod. What are you trying to do?

[BinaryCPG]

You need an Event Listener for a World getting loaded.

Try it like this:

 

ExampleMod Class:

@EventHandler

public void init(FMLInitializationEvent event){

    MinecraftForge.EVENT_BUS.register(new WorldEventListener());

}

 

WorldEventListener Class:

@SubscribeEvent

public void worldLoaded(WorldEvent.Load event){

    event.world.setBlock(0, 70, 0, Blocks.cactus, 1, 2);

    // every time a world gets loaded this method is gonna get called

}

[ForgeNewbie]

@BinaryCPG:  THANK YOU!!!  That worked perfectly!  Do you know of a book that teaches those kinds of nuts and bolts? 

 

@Anon10W1z:  Thanks for your reply.  What you said makes perfect sense. 

 

To answer your question:  Basically I was just trying to create a building (house, ship, whatever) from code so that I could force it to appear in any of my existing worlds exactly where I tell it too, without having to rebuild it manually in the game.    Now I can  :-)