Good evening guys,

 

I want to go back to the title screen (just for test purpose) when the ServerStartingEvent gets triggered, but then it crashes and this error gets printed:

Spoiler

Quote

java.lang.NullPointerException: Cannot invoke "net.minecraft.client.Minecraft.isDemo()" because "this.minecraft" is null
    at net.minecraft.client.gui.screens.TitleScreen.render(TitleScreen.java:366) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraftforge.client.ForgeHooksClient.drawScreenInternal(ForgeHooksClient.java:385) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2375%2381!/:?] {re:classloading}
    at net.minecraftforge.client.ForgeHooksClient.drawScreen(ForgeHooksClient.java:378) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2375%2381!/:?] {re:classloading}
    at net.minecraft.client.renderer.GameRenderer.render(GameRenderer.java:900) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.runTick(Minecraft.java:1070) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.doLoadLevel(Minecraft.java:2012) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.loadLevel(Minecraft.java:1913) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.gui.screens.worldselection.WorldSelectionList$WorldListEntry.loadWorld(WorldSelectionList.java:473) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.gui.screens.worldselection.WorldSelectionList$WorldListEntry.joinWorld(WorldSelectionList.java:330) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.gui.screens.worldselection.WorldSelectionList$WorldListEntry.mouseClicked(WorldSelectionList.java:257) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.gui.components.AbstractSelectionList.mouseClicked(AbstractSelectionList.java:323) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.gui.components.events.ContainerEventHandler.mouseClicked(ContainerEventHandler.java:31) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.MouseHandler.lambda$onPress$0(MouseHandler.java:93) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.gui.screens.Screen.wrapScreenError(Screen.java:528) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.MouseHandler.onPress(MouseHandler.java:90) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.MouseHandler.lambda$setup$4(MouseHandler.java:195) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.util.thread.BlockableEventLoop.execute(BlockableEventLoop.java:90) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B}
    at net.minecraft.client.MouseHandler.lambda$setup$5(MouseHandler.java:194) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36) ~[lwjgl-glfw-3.2.2.jar%2354!/:build 10] {}
    at org.lwjgl.system.JNI.invokeV(Native Method) ~[lwjgl-3.2.2.jar%2360!/:build 10] {}
    at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:3101) ~[lwjgl-glfw-3.2.2.jar%2354!/:build 10] {}
    at com.mojang.blaze3d.systems.RenderSystem.flipFrame(RenderSystem.java:168) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at com.mojang.blaze3d.platform.Window.updateDisplay(Window.java:337) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.runTick(Minecraft.java:1092) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.Minecraft.run(Minecraft.java:668) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.main.Main.main(Main.java:205) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.11.06-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:runtimedistcleaner:A}
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] {}
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[?:?] {}
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] {}
    at java.lang.reflect.Method.invoke(Method.java:568) ~[?:?] {}
    at net.minecraftforge.fml.loading.targets.ForgeClientUserdevLaunchHandler.lambda$launchService$0(ForgeClientUserdevLaunchHandler.java:24) ~[fmlloader-1.18.2-40.1.0.jar%230!/:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:53) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:71) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.modlauncher.Launcher.run(Launcher.java:106) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.modlauncher.Launcher.main(Launcher.java:77) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23) [modlauncher-9.1.3.jar%2310!/:?] {}
    at cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:149) [bootstraplauncher-1.0.0.jar:?] {}

 

 

My Event Class:

@Mod.EventBusSubscriber(modid = EdomRpMod.MOD_ID)
public class ModEvents {
    @SubscribeEvent
    public static void onServerStarting(ServerStartingEvent event){
        Minecraft.getInstance().setScreen(new TitleScreen());
    }
}

 

EDIT: Add error stack trace

 

Does anyone know how to switch screens between the main menu and other screens (no ingame overlay)?

Edited February 16, 20232 yr by J3ramy

15 hours ago, J3ramy said:

        Minecraft.getInstance().setScreen(new TitleScreen());

For clarity sake, client side classes like Minecraft do not exist on the server. You can set the screen on the client through the methods you are showing yes, but only in client side events. Why are you trying to do this when the server starts up?

I am programming a mod which checks if the player is whitelisted via database query. And in the ServerStartingEvent I want to check if the connection can be established  - if not, then switch back to the title screen

 

EDIT: I found the ClientPlayerNetworkEvent.LoggedInEvent which is client only. There, I can also disconnect the player from the server immediately via ClientPlayerNetworkEvent.LoggedInEvent#getConnection()#disconnect(Component)

Edited February 16, 20232 yr by J3ramy

19 hours ago, J3ramy said:

I am programming a mod which checks if the player is whitelisted via database query. And in the ServerStartingEvent I want to check if the connection can be established  - if not, then switch back to the title screen

Why not just use a whitelist that already exists in Vanilla?

Because in my case the whitelist state for players depends on a special database

I would just use PlayerEvent$PlayerLoggedInEvent then and call disconnect from the player there since the connection happens on the server.