How to remove the prefix path name when packing classes into a jar by jar command?

Question

For example:

$ tree obj/
obj/
└── com
    ├── deps
    │   └── Dog.class
    └── test
        └── Main.class

3 directories, 2 files

I want add com/deps/Dog.class and com/test/Main.class to my target.jar file. I always cd the obj path then run:

$ cd obj
$ jar cvf ../target.jar .
added manifest
adding: com/(in = 0) (out= 0)(stored 0%)
adding: com/test/(in = 0) (out= 0)(stored 0%)
adding: com/test/Main.class(in = 506) (out= 352)(deflated 30%)
adding: com/deps/(in = 0) (out= 0)(stored 0%)
adding: com/deps/Dog.class(in = 908) (out= 507)(deflated 44%)

If I run jar target.jar obj/ in current directory:

$ jar cvf target.jar obj/
added manifest
adding: obj/(in = 0) (out= 0)(stored 0%)
adding: obj/com/(in = 0) (out= 0)(stored 0%)
adding: obj/com/test/(in = 0) (out= 0)(stored 0%)
adding: obj/com/test/Main.class(in = 506) (out= 352)(deflated 30%)
adding: obj/com/deps/(in = 0) (out= 0)(stored 0%)
adding: obj/com/deps/Dog.class(in = 908) (out= 507)(deflated 44%)

Noticed that an invalid prefix path obj added. Is there any argument can remove obj/ from the entries?