I installed forge with the installed, play the game, it gives me the FML early loading progress loading window, then this happens:

 

---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 12/2/2020, 7:43 pm
Description: Initializing game

java.lang.ExceptionInInitializerError: null
	at net.minecraftforge.fml.ModLoader.<init>(ModLoader.java:121) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.ModLoader.get(ModLoader.java:146) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.client.ClientModLoader.lambda$begin$2(ClientModLoader.java:97) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraftforge.fml.client.ClientModLoader.lambda$createRunnableWithCatch$5(ClientModLoader.java:113) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraftforge.fml.client.ClientModLoader.begin(ClientModLoader.java:97) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
	at net.minecraft.client.Minecraft.<init>(Minecraft.java:393) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
	at net.minecraft.client.main.Main.main(SourceFile:166) ~[1.15.2-forge-31.1.1.jar:?] {re:classloading}
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] {}
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?] {}
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] {}
	at java.lang.reflect.Method.invoke(Method.java:567) ~[?:?] {}
	at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:56) ~[forge-1.15.2-31.1.1.jar:31.1] {}
	at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-5.0.0-milestone.4.jar:?] {}
	at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-5.0.0-milestone.4.jar:?] {}
	at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-5.0.0-milestone.4.jar:?] {}
	at cpw.mods.modlauncher.Launcher.run(Launcher.java:81) [modlauncher-5.0.0-milestone.4.jar:?] {}
	at cpw.mods.modlauncher.Launcher.main(Launcher.java:65) [modlauncher-5.0.0-milestone.4.jar:?] {}
Caused by: java.lang.IllegalStateException: Failed to resolve consumer event type: net.minecraftforge.fml.network.simple.SimpleChannel$$Lambda$2213/0x000000080139e840@59d29065
	at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:194) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
	at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:161) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
	at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:156) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
	at net.minecraftforge.eventbus.EventBus.addListener(EventBus.java:151) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
	at net.minecraftforge.fml.network.NetworkInstance.addListener(NetworkInstance.java:65) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.simple.SimpleChannel.<init>(SimpleChannel.java:56) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.simple.SimpleChannel.<init>(SimpleChannel.java:49) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.NetworkRegistry$ChannelBuilder.simpleChannel(NetworkRegistry.java:409) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.NetworkInitialization.getHandshakeChannel(NetworkInitialization.java:38) ~[?:?] {re:classloading}
	at net.minecraftforge.fml.network.FMLNetworkConstants.<clinit>(FMLNetworkConstants.java:48) ~[?:?] {re:classloading}
	... 17 more


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

-- Head --
Thread: Render thread
Stacktrace:
	at net.minecraftforge.fml.ModLoader.<init>(ModLoader.java:121)
	at net.minecraftforge.fml.ModLoader.get(ModLoader.java:146)
	at net.minecraftforge.fml.client.ClientModLoader.lambda$begin$2(ClientModLoader.java:97)
	at net.minecraftforge.fml.client.ClientModLoader.lambda$createRunnableWithCatch$5(ClientModLoader.java:113)
	at net.minecraftforge.fml.client.ClientModLoader.begin(ClientModLoader.java:97)
	at net.minecraft.client.Minecraft.<init>(Minecraft.java:393)

-- Initialization --
Details:
Stacktrace:
	at net.minecraft.client.main.Main.main(SourceFile:166)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:56)
	at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37)
	at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54)
	at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72)
	at cpw.mods.modlauncher.Launcher.run(Launcher.java:81)
	at cpw.mods.modlauncher.Launcher.main(Launcher.java:65)

-- System Details --
Details:
	Minecraft Version: 1.15.2
	Minecraft Version ID: 1.15.2
	Operating System: Linux (amd64) version 5.5.0-050500-generic
	Java Version: 13.0.2, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode, sharing), Oracle Corporation
	Memory: 446085840 bytes (425 MB) / 1040187392 bytes (992 MB) up to 2147483648 bytes (2048 MB)
	CPUs: 8
	JVM Flags: 8 total; -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	Launched Version: 1.15.2-forge-31.1.1
	Backend library: LWJGL version 3.2.2 build 10
	Backend API: AMD RAVEN (DRM 3.36.0, 5.5.0-050500-generic, LLVM 9.0.0) GL version 4.5 (Compatibility Profile) Mesa 19.2.8, X.Org
	GL Caps: Using framebuffer using OpenGL 3.0
	Using VBOs: Yes
	Is Modded: Definitely; Client brand changed to 'forge'
	Type: Client (map_client.txt)
	CPU: 8x AMD Ryzen 7 PRO 3700U w/ Radeon Vega Mobile Gfx

 

Although I am a CS student, I am not familiar with Java yet... so I seek help here and hope the devs knows it.

49 minutes ago, diesieben07 said:

Java 13 is not yet supported.

Please stick to Java 8 for now, which is the version also targed by Mojang.

 

You can get OpenJDK builds from AdoptOpenJDK, make sure to get the JRE, you don't need the JDK unless you want to develop Java applications. 

Thanks, it works now! Looks like write once run anywhere is a fantasy. Appreciate your quick response.