Can a landlord require a tenant to pay the full value of a year’s lease if the tenant needs to terminate the lease prior to it’s expiration?

You are NOT liable for the rent for the entire year.  You are only liable for the rent until the place is re-rented.  Once the place is re-rented, your obligation to pay rent ends.  The landlord has to mitigate (minimize) damages (the amount the landlord claims you owe) by making reasonable efforts to find another tenant.  The landlord cannot allow the place to remain vacant for the balance of the term of your lease without making reasonable efforts to find another tenant.  Reasonable efforts to find another tenant will be determined by what other landlords in the area are doing to attract tenants; for example, posting a sign on the property advertising the vacancy, advertising the vacancy in the newspaper, online, in a local rental guide, etc.  If the landlord does not make reasonable efforts to find another tenant, the landlord has failed to mitigate damages and the landlord's damages will be reduced accordingly.  If the landlord allows the place to remain vacant for the balance of the term of your lease without making reasonable efforts to find another tenant, the landlord has failed to mitigate damages, and the landlord's damages will be reduced accordingly.

The landlord cannot collect double rent (rent from you and a new tenant once the place has been re-rented).  As mentioned above, once the place is re-rented your obligation to pay rent ends.  If the new tenant is paying less rent than you were paying, you are liable for the difference in rent for the balance of the term of your lease, but only if the landlord has a valid reason for charging the new tenant less rent, such as market conditions.  If the landlord does NOT have a valid reason for charging the new tenant less rent than you were paying, the landlord has failed to mitigate damages and you won't be liable for the differnce in rent for the balance of the term of your lease.