Minecraft Java Edition key is meant to be activated on the official Minecraft website.
To activate the Minecraft java key:
 
Go to https://minecraft.net/en-us/redeem/
Click "Redeem Java Edition"
Click "register for a Mojang account" or login if you already have an account.
Choose "redeem gift code or prepaid card" option and type in your code. Please remember to type the cd key without spaces nor pauses.
 
Minecraft Java Edition is one of the two official versions of the sandbox survival game, released in 2011 by Mojang Studios for PC. Enter the unbelievably massive world of cubes and design it the way you want. Select a relaxed, creative mode or fight monsters in Survival mode. Solo or in multiplayer - in Minecraft, you can do anything!
 
Minecraft Java Edition
 
There are two versions of Minecraft available: Bedrock Edition and Java Edition. Although very similar, they differ in several features. Minecraft Java Edition is the oldest and first version from Mojang providing cross-platform gameplay between Windows, Linux, and macOS. What's more, Java Edition allows you to make many modifications and new game modes that are completely free. Such features in Bedrock are available in the micropayment system.
 
Key features
 
Potentially endless world for the players to explore. Procedurally generated as you travel further, always keeps something to surprise you with.
Several game modes, each catering to a different gameplay, from survival to exploration to boundless creation. Join up with friends and together create wonders.
Interact with mobs, from wildlife to monsters, Minecraft makes sure you never feel alone in its vast world. Fight them, herd them or eat them, you are the king of the land.
Other dimensions to explore, the Nether and the End Realm wait just on the other side of portals you can create.
Day and night cycle changes the game between safe exploration and a fight for survival when the monsters come at night.
Discover the world of cubes and create without limits
Explore and collect valuable resources
Learn new crafting designs to build even better structures and items
Choose a game mode that meets your expectations
Play solo or in multiplayer with other players