In which Programming Language Android had Developed I don't know this question has asked before or not.
The programming language had used to develop android open source project. 

I try to find out the answer of this question many times but still unable to find out the answer.

I know we are developing android apps in java and also know that the base of android is linux.

Any Idea 

Thank You
As mentioned on it's Wikipedia page, Android's core is developed in C and C++, and Java is used for the UI. You can see this for yourself if you browse the Android source code. For example, omapzoom.org provides the source for browsing without the need to downloads gigabytes of data.