Start

This class is how the game is able to start within the ide

main

The method which starts the game

public static void main(String[] args)
{
    /*
    * start minecraft game application
    * --version is just used as 'launched version' in snoop data and is required
    * Working directory is used as gameDir if not provided
    */
    String assets = System.getenv().containsKey("assetDirectory") ? System.getenv("assetDirectory") : "assets";
    Main.main(concat(new String[]{"--version", "mcp", "--accessToken", "0", "--assetsDir", assets, "--assetIndex", "8", "--userProperties", "{}"}, args));
}

concat

public static <T> T[] concat(T[] first, T[] second)
{
    T[] result = Arrays.copyOf(first, first.length + second.length);
    System.arraycopy(second, 0, result, first.length, second.length);
    return result;
}