How do i get my puppy to stop whining when we leave?

We just adopted a boxer mix and have not left her alone for a long period of time yet but when we left for the grocery we came back and heard her whining from outside.I know that at her foster she had 4 other dogs with her and I do not think she was left alone a lot. Also, we live in an apartment so I do not want to disturb the people below or above me. How do i get her to stop whining so loudly?