Why did Google have choose Java as Android's Native language?

[tamilarasu]

Why did Google have choose Java as Android's Native language?
-Can we write applications for Android in languages other than Java.

-In What language its user interface is developed? (i know Most of it's core libraries are developed in C++)

[Jan]

Why was Java chosen? Probably because of its portability. As many mobile operating systems come with the JVM, Google had a head start thanks to Java, as apps for other systems could be easily ported.

Can we write in other languages? Yes, of course, if we couldn't, Android would be a no-go for devs who hate C++ syntax. While there is no official interpreter for, for example Ruby or Python, for Android, there are versions of them that compile to Java bytecode, or frameworks to integrate them with the OS.

User interfaces are not developed in languages per se. In order to draw anything on-screen you need to have a library that talks to the graphical unit. I suspect they used SDL or Qt.