In android How to track the other people using GPS?

I want to track my friend using GPS when he is 1 or 2 km far from me. Is there any help or link to solve this problem I goggled it allot but can't be able to find more appropriate informa开发者_StackOverflowtion about this please tell me how can i do this or what is the best approach (api) to solve this.

Thanks

Without that persons or network provider permission you cant access there gps location. Its only solution that your friend and you both using a any android application which has a GPS feature an sharing a location. Thanks.