Which programming languages should i learn to make os and andriod applications.

Answer 1

to make an OS:
C, Assembly, Machine Code

to make Android apps:
Java, Kotlin, XML(?)

Answer 2

C#. I've created one just for fun in JavaScript. Check it out :P

Answer 3

Java and Xml. Currently I am using these two to make android apps.

Answer 4

how can I get XML ?
please tell me.

Answer 5

You can learn android from udacity's free android course. I learnt from there. You will learn both Xml and java implementation.