Why am I getting null pointers here?

This is a plugin that will spawn space meteors. Nowhere in that code do I see any sort of null. All I did was create a second class named MeteorTimer and extended it to a BukkitRunnable. One reason I believe why I'm getting a nullpointer is because I didn't set the constructor to anything, I don't know if I need to really do anything with it or not, I just know it should be there. If anything belongs in there could someone elaborate as to why it is needed? Thank you!

Here is my onEnable():

Code:java

public void onEnable() {
meteorBlocks.add(Material.DIAMOND_ORE);
meteorBlocks.add(Material.GOLD_ORE);
meteorBlocks.add(Material.COAL_ORE);
meteorBlocks.add(Material.STONE);
meteorBlocks.add(Material.DIRT);
meteorBlocks.add(Material.GLOWSTONE);
meteorBlocks.add(Material.WOOL);
 
MeteorTimer mt = new MeteorTimer();
 
int r = (int) (Math.random() * 30);
int x = (int) (Math.random() * 2000);
int y = (int) (Math.random() * 230);
int z = (int) (Math.random() * 2000);
int v = (int) (4 / 3 * 3.14 * r * r);
 
World w = Bukkit.getServer().getWorld(Bukkit.getServerName());
Location loc = new Location(w, x, y, z);
 
generateSphere(loc, r);
@SuppressWarnings("deprecation")
Player p = Bukkit.getServer().getPlayer(Bukkit.getServerName());
p.sendMessage(ChatColor.BLUE + "Meteors:" + ChatColor.WHITE
+ " New meteor has been located at " + x + " " + y + " " + z
+ ". Meteor size is roughly: " + v + " blocks.");
mt.runTaskTimer(this, LONG_DELAY, LONG_PERIOD);
//out.print("METEOR SPAWNED!");
 
}

My MeteorTimer class:

Code:java

public class MeteorTimer extends BukkitRunnable{
 
public MeteorTimer(){
// what goes here?
}
 
 
@Override
public void run() {
 
 
}
 
 
 
 
 
}

generateSphere method:

Code:java

public static List<Location> generateSphere(Location centerBlock, int radius) {
        List<Location> centerBlocks = new ArrayList<Location>();
 
        int bX = centerBlock.getBlockX();
        int bY = centerBlock.getBlockY();
        int bZ = centerBlock.getBlockZ();
        for (int x = bX - radius; x <= bX + radius; x++) {
            for (int y = bY - radius; y <= bY + radius; y++) {
                for (int z = bZ - radius; z <= bZ + radius; z++) {
 
                    double distance = ((bX - x) * (bX - x))
                            + ((bZ - z) * (bZ - z) + ((bY - y)) * (bY - y));
 
                    if (distance < radius * radius
                            && !(distance < ((radius - 1) * (radius - 1)))) {
 
                        for (Location l : generateSphere(centerBlock, radius)) {
                            Material type = meteorBlocks.get((int) (Math
                                    .random() * meteorBlocks.size()));
                            l.getBlock().setType(type);
 
                            centerBlocks.add(l);
 
                        }
                    }
 
                }
 
            }
 
        }
        return centerBlocks;
    }
 
}
 

Edit: I was getting a nullpointer but I ran into another problem in my stack trace log:

Code:

71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]
        at me.huffmanbran.bukkit.five.MeteorCore.generateSphere(MeteorCore.java:
71) ~[?:?]

Thank you for the help!

 

Post your generateSphere method.

 

Here you are:

Code:java

public static List<Location> generateSphere(Location centerBlock, int radius) {
        List<Location> centerBlocks = new ArrayList<Location>();
 
        int bX = centerBlock.getBlockX();
        int bY = centerBlock.getBlockY();
        int bZ = centerBlock.getBlockZ();
        for (int x = bX - radius; x <= bX + radius; x++) {
            for (int y = bY - radius; y <= bY + radius; y++) {
                for (int z = bZ - radius; z <= bZ + radius; z++) {
 
                    double distance = ((bX - x) * (bX - x))
                            + ((bZ - z) * (bZ - z) + ((bY - y)) * (bY - y));
 
                    if (distance < radius * radius
                            && !(distance < ((radius - 1) * (radius - 1)))) {
 
                        for (Location l : generateSphere(centerBlock, radius)) {
                            Material type = meteorBlocks.get((int) (Math
                                    .random() * meteorBlocks.size()));
                            l.getBlock().setType(type);
 
                            centerBlocks.add(l);
 
                        }
                    }
 
                }
 
            }
 
        }
        return centerBlocks;
    }
 
}
 

 

What is line 71 of the class?

 

Code:java

for (Location l : generateSphere(centerBlock, radius)) {

 

Huffmanbran Hmm... weird. I don't see any possible NPEs. I do see a possible IndexOutOfBoundsException though with:

Code:java

meteorBlocks.get((int) (Math
                                    .random() * meteorBlocks.size()))

And the reason you are getting spammed with the same console message is because you created a recursive method without a stopping point. Are you sure you are getting an NPE? This thread will help you with stack-traces a bit more. http://forums.bukkit.org/threads/ho...ubleshoot-your-own-plugins-by-yourself.32457/

 

I did have an NPE, but the recursive method spams the NPE exception error out of the console. I'll just fix the recursive method real quick and give you the NPE exception.

Couldn't you just stop it by adding an if else? I don't seem to know how to stop it apparently :/

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Huffmanbran

Can't you just break; it?

 

Huffmanbran the recursion is useless (it breaks your code without adding any functionality), just remove it.

 

You are adding an if statement to prevent recursion, (I'm too lazy to do the math if the test would even work ), your problem is you are putting in the exact same arguments in your recursive call as your initial method call. Nothing is changing.

 

I have gotten rid of it. And it got rid of my StackOverFlow error. Here is the NPE:

Code:

java.lang.NullPointerException
        at me.huffmanbran.bukkit.five.MeteorCore.onEnable(MeteorCore.java:43) ~[
?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:316) ~[s
pigot.jar:git-Spigot-1649]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader
.java:332) [spigot.jar:git-Spigot-1649]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManage
r.java:417) [spigot.jar:git-Spigot-1649]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugin(CraftServer.jav
a:476) [spigot.jar:git-Spigot-1649]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.enablePlugins(CraftServer.
java:394) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.MinecraftServer.n(MinecraftServer.java:3
60) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.MinecraftServer.g(MinecraftServer.java:3
34) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.MinecraftServer.a(MinecraftServer.java:2
90) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.DedicatedServer.init(DedicatedServer.jav
a:210) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java
:458) [spigot.jar:git-Spigot-1649]
        at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:6
28) [spigot.jar:git-Spigot-1649]

I know the nullpointer is being causing somewhere in the onEnable() method.

 

Huffmanbran What's line 43 of MeteorCore? Is MeteorCore your main class?

Also, please show us your full classes, not just parts of it. It would really help.

 

Huffmanbran is there a Player with the same name as your server? If no, then that is the reason ;3.

 

Yeah it's because I instantiated the player as the server name for some reason.. -.-

Code:java

Player p = Bukkit.getServer().getPlayer(Bukkit.getServerName());

Edit: What would I need to set in this code in order to retrieve the player and its name?

 

Huffmanbran

Code:java

Player p = Bukkit.getServer().getPlayer().getDisplayName();

Should work

 

WesJD Why are you assigning a String object to a Player?

Huffmanbran You can't do it on the onEnable unless you reload your server with a player, otherwise you'll need to do it elsewhere, either a PlayerLoginEvent or something like that.

 

So could I set it to where when the player logs in it will store their name into an array or something? And when that method is called it will check if the player is in the array or another data storage? Would that work?

 

Konato_K Oh, I thought that's what he wanted? My bad.

 

Huffmanbran wouldn't you want to spawn the meteor on an event or command instead of onEnable in the first place?

 

Well I got it to run, turns out I'm just not going to use Player, I don't need to.
Here is the successful stacktrace:

Code:

[20:00:05 INFO]: [Meteors] Enabling Meteors v1.0
[20:00:05 INFO]: [Meteors] New meteor spawned at 996 76 1428
[20:00:05 INFO]: [Meteors] Size of meteor: 1256 blocks!

Yet, at that location there is no sign of a meteor or a single block containing in the list of materials that the meteor will be made of. Why is it not generating the blocks?

Here is my generateSphere method:

Code:java

public static List<Location> generateSphere(Location centerBlock, int radius) {
List<Location> centerBlocks = new ArrayList<Location>();
 
int bX = centerBlock.getBlockX();
int bY = centerBlock.getBlockY();
int bZ = centerBlock.getBlockZ();
for (int x = bX - radius; x <= bX + radius; x++) {
for (int y = bY - radius; y <= bY + radius; y++) {
for (int z = bZ - radius; z <= bZ + radius; z++) {
 
double distance = ((bX - x) * (bX - x))
+ ((bZ - z) * (bZ - z) + ((bY - y)) * (bY - y));
 
if (distance < radius * radius
&& !(distance < ((radius - 1) * (radius - 1)))) {
 
centerBlocks.add(centerBlock);
 
}
 
}
 
}
 
}
return centerBlocks;
}
 
}
 

 

Huffmanbran generateSphere just returns a List of Locations... with a lot of centerBlock in it (note that all these will be the same). It doesn't change any block or spawn any entity.

 

What if I added:

Code:java

for (Location l : generateSphere(centerBlock, radius)) {
Material type = meteorBlocks
.get((int) (Math.random() * meteorBlocks.size()));
l.getBlock().setType(type);
 
centerBlocks.add(centerBlock);
 
//note this function is in the generateSphere method
 

Edit: I added it, now I get a StackOverFlow..

 

Huffmanbran invoke it in onEnable (where you get your List<Location> from the generateSphere method)