Disclosure: I've never played Bedrock. Ever. So I don't know what I am talking about half of the time. Needless to say, Bedrock players know Bedrock best.

I don't use a Mac, so I have no idea how to do there. While my setup is an open-source Arch-alike system using ZSH for user shell, it lends me no experience with OS X.

Introduction

For people who are woefully attached to their controllers and wouldn't ever think they'd enjoy Java Edition without one, by default it isn't possible to use a gamepad. Fortunately, there are some people in the modding scene which made some great mods for the game, and so long you aren't immediately interested in modding with Forge, Fabric is a great platform to help make possible the implementation of controller support, and to make the game feel almost exactly like Bedrock.

Mind the word, almost. This guide will help you get there as close as you can on Java Edition, though some interface elements are going to be very different. For best couch-gaming results, use an Xbox One 1697 or 1708 gamepad (or similar) with chatpad attachment or Playstation 4 CHU-ZCT1 (or similar) with optional controller-attached keyboard accessory. (Used market is full of cheap OEM / ODM parts.)

Installing Fabric

Follow the advice here. Opening the JAR file using the copy of Java 8 JRE provided by Minecraft is not necessary if you already have Java stand-alone, in which case the executable binary for that can be used instead. For Linux and Mac OS X users, Java should already be available via the command line.

Default launcher brief

Before using Fabric loader you may be interested in changing its game directory. Fabric loader should be made available and using this icon:

For Mojang's launcher, Under Installations, click on the ellipsis (…) and choose to Edit.

Why yes, I do have a lot of installation profiles. Lots of stuff is shared between directories with symlinks.

While you don't have to go that crazy with profiles, I tend to have a bunch of extra stuff. For you, it'll probably be just vanilla and Fabric — Edit fabric.

Choose to browse for a directory, and put content elsewhere. If you want to be as hyper-organized as I am, you can typically use .minecraft/versions as an existing directory location to keep stuff — Pick where Fabric-modded Minecraft is and for other profiles using the same build of the game, placing subdirectories there isn't a bad idea.

Mods

Once everything is how you want it, go into the game directory you had assigned for Fabric and if it doesn't exist already, create a directory named mods. From there, you'll want to put into that directory the following four mods:
Fabric API
Mod Menu
BedrockIfy
LambdaControls

OptiFabric notes

If you take an interest to OptiFine and resource packs for / enhanced by it, I've written a blog entry about resolving incompatibility issues with LambdaControls. You might want to read it.

External software

LambdaControls will not work immediately. For that you will need to execute the game and follow the URL provided in LambdaControls' settings, accessible from Mod Menu. If you'd rather do this first before opening the game, click this link to download a copy of General Arcade's Gamepad Tool for your operating system / kernel in use.

Follow its use instructions after execution and choose to Copy mapping string. This can be saved into a text document as /config/gamecontrollerdb.txt or kept in system clipboard until ready to paste into the screen shown after clicking on Open Mappings File Editor:

The Mappings File Editor screen. Yes, it's just an empty, black void what about it? Also the capture is outdated.

Mod settings

The below settings may be of interest to people who are attempting to emulate the Bedrock experience in Java and / or ween themselves off of Bedrock / gamepad use:

BedrockIfy

Reach-Around block placement
This can be disabled in one of two ways:

From BedrockIfy General tab

• Enable Reach-Around: No

From BedrockIfy Mixins tab

• client.features.reacharoundPlacement: No
  

Reason: LambdaControls includes its own reach-around mechanics.

Other settings

• Show BedrockIfy settings button: No
  Reason: It's one more button which is wholly unnecessary because of Mod Menu.
• Use Bedrock Crafting Recipes: No
  Reason: Transitioning away from Bedrock means also letting old habits die.

LambdaControls

Note: LambdaControls rearranges locations of buttons in-game. Though all of this really applies for transitioning away from joypads and to keyboard+mouse, a full keyboard layout is also possible for people with limited desk space and no interest in using a joypad at all should they want.

Controls… / Keyboard Controls…

• BedrockIfy / Open BedrockIfy Settings: Not Bound
  Reason: What if you want to use B for something else? Also, could interfere with typing. (Had that happen multiple times!)

Controls... / Options...

• General Options / Auto-Switch mode: On
  Acclimate yourself to not using a pad, and if you don't like it, plug the controller back in without changing in settings.
• Gameplay Options / Auto-Jump: Off
  Most PC players prefer this off, so it is a good transitioning provision to emulate this.
• Gameplay Options / Front Block Placing: On
  See an outline of the block ahead to place in mid-air. Bedrock control feature.
• Gameplay Options / Vertical Reacharound: On
  Be able to place a block beneath you, from above. Bedrock feature.
• HUD Options / Enable HUD: Off
  Become familiar with the controls and this won't be necessary: Removes screen clutter.

Adjust everything else to preference.

What to do now?

Load a single-player world and see if you can get along with Java Edition, now that it is more like Bedrock. Over time, you can adjust settings for both BedrockIfy and LambdaControls so either you can affirm your controller-using habits, or ween yourself off of it and play Java with a keyboard.

While it could be considered cheating, the reach-around features are handy to get oneself out of a bind and build better in a single-player world. Though, some multiplayer servers may check for this and consider such movements as "Irregular" and kick you for attempting to play the game like Bedrock on Java. Consult your server administrator about this to adjust for Bedrock player compliance or seek another multiplayer server elsewhere.

Image credits

Thumbnail icons

Fabric logo: Fabric Project
Bedrock block: Mojang, Minecraft Wiki

Screencap

Stay True texture pack by Trrigg
VanillaTweaks