public class BlockUsaPortal extends Block{
	
	public BlockUsaPortal(Properties properties){
		super(properties);
	}
	
	public boolean hasTileEntity(BlockState state){
		return true;
	}
	public TileEntity createTileEntity(BlockState state, IBlockReader world) {
		return ModTileEntityTypes.USAPORTAL.get().create();
	}
	public void onEntityCollision(BlockState state, World worldIn, BlockPos pos, Entity entityIn) {
	      if (!worldIn.isRemote && !entityIn.isPassenger() && !entityIn.isBeingRidden() && entityIn.isNonBoss() && VoxelShapes.compare(VoxelShapes.create(entityIn.getBoundingBox().offset((double)(-pos.getX()), (double)(-pos.getY()), (double)(-pos.getZ()))), state.getShape(worldIn, pos), IBooleanFunction.AND)) {
	         entityIn.changeDimension(worldIn.dimension.getType() == DimensionType.OVERWORLD ? DimensionType.OVERWORLD : (DimensionType) DimensionInit.USA_DIMENSION.get().getFactory());
	         
	      }
	}

	      
}

So I'm trying to make a portal for a custom dimension. Right now I'm just trying to get it to teleport you to this dimension when you touch it, and so far that's not working. When I come into contact with this block in the overworld, all it does is spawn a nether portal where I'm standing (or teleports me to a nearby one). If I try to do it in the custom dimension the game crashes. Any advice on how I can get this to work properly is appreciated.

For the teleport code, just look into the /forge setdimension command. That should help.

The file is called "net.minecraftforge.server.command.CommandSetDimension.java"

 

I figured it out by looking at the dimension manager class. 

entityIn.changeDimension(worldIn.dimension.getType() == DimensionType.OVERWORLD ? DimensionManager.registerOrGetDimension(racismmod.USA_TYPE, DimensionInit.USA_DIMENSION.get(), null, true) : DimensionType.OVERWORLD);