Is there an event that runs when the main menu is started or after initialization completes where I can get the players uuid??

 

While I'm at it, how do I verify that the user is actually logged in though mojang?

There events fired after game initialization, but why do you need their UUID ? And why do you want to see if the players is logged in ?

i'm trying to connect to a 3rd party application for authentication

Minecraft.getMinecraft().thePlayer.getGameProfile()

The event you are looking for should be GuiOpendedEvent (or sth like that) there you should check if The opened gui is The Main Menu.

Have in mind that The player comes back to The Main Menu when logging out of a game, so you should check if your player is already logged in that 3rd Party thingy

The name of the event is InitGuiEvent, but you can also use the postInitializationEvent

I am getting

Time: 6/22/15 5:19 PM
Description: Initializing game

java.lang.NullPointerException: Initializing game
at com.ssttevee.blockbank.EventHookContainer.onGuiOpen(EventHookContainer.java:27)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_8_EventHookContainer_onGuiOpen_GuiOpenEvent.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:55)
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:138)
at net.minecraft.client.Minecraft.displayGuiScreen(Minecraft.java:961)
at net.minecraft.client.Minecraft.startGame(Minecraft.java:538)
at net.minecraft.client.Minecraft.run(Minecraft.java:356)
at net.minecraft.client.main.Main.main(Main.java:117)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
at net.minecraftforge.gradle.GradleStartCommon.launch(Unknown Source)
at GradleStart.main(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
at com.ssttevee.blockbank.EventHookContainer.onGuiOpen(EventHookContainer.java:27)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_8_EventHookContainer_onGuiOpen_GuiOpenEvent.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:55)
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:138)
at net.minecraft.client.Minecraft.displayGuiScreen(Minecraft.java:961)
at net.minecraft.client.Minecraft.startGame(Minecraft.java:538)

-- Initialization --
Details:
Stacktrace:
at net.minecraft.client.Minecraft.run(Minecraft.java:356)
at net.minecraft.client.main.Main.main(Main.java:117)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
at net.minecraftforge.gradle.GradleStartCommon.launch(Unknown Source)
at GradleStart.main(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

 

relevant code

    @SubscribeEvent
    public void onGuiOpen(GuiOpenEvent event) {
        if(event.gui instanceof GuiMainMenu) {
            System.out.println(Minecraft.getMinecraft().thePlayer.getGameProfile());
        }
    }

Try replacing your System.out with a simple text string, like System.out.println("Hello!");

 

Then read in the console and see if you are on the client side or the server side.

it is on the client side

I got it.  If anyone needs it, it's:

Minecraft.getMinecraft().getSession().getProfile()