What is a programming language for android?

Android is basically an open-source operating system. When you say open-source, you can develop and market apps without any license.

For developing android apps, we usually use either eclipse or Android Studio software. You need to have hands-on knowledge of Java and preferably XML. If you're developing apps based on Java, you can create SDK apps which are highly marketed by google. However, you can build apps using C/C++ but you will be developing NDK apps.

If I have to recommend, i can say you develop SDK apps using Android Studio. Android Studio is free and can be downloaded from Android site which runs on all latest operating system(Windows and Mac). They also have a tutorial site where you can learn how to build apps. I would recommend you have a knowledge on java and xml.

Now, why do you need to develop apps. Its simple. They are free and many people build their own revenue by selling apps. You can create apps with ideas of your own, and can sell them on Google Store. If your app is good enough, you can make a decent revenue out of your apps.

The base language in which the Android OS is written is in Java. So the primary language for developing the app and the extensions are limited to Java. However the API also extends in such way that you can use the other programming languages to write the code for app or extension within the Android platform itself. Most of the supported languages are - C#, Python, Ruby, Scala and Javascript (along with HTML5).

C# Port of Android is known as Xamarin. So you can use the .NET code to design the android app. It is very easy to write the app using Xamarin development if you're comfortable with C#. Installation procedure for Xamarin is explained on the official documentation. It is very easy and all need to do is install Android SDK and then download Xamarin.

QPython is the python port for Android. Scripting nature of Python makes it easy to write Android code. You can make complete apps, patches and extension using QPython. Installation The installation is to be done on Android Phone itself. So you can run the python scripts inside the Android. Mostly this is used by the testers and patch developers.

Ruby - In case of Ruby there are two ports for Android namely - Ruboto and RubyMotion. Rubymotion is not necessarily an Android specific port. But it can help export the ruby code to Android. As for Ruboto you can create and run Android specific code and apps using this framework. The installation is very simple and you just have to run the installer for these frameworks.

Javascript - There are literally hundreads of forks out there for Javascript. You can find lot of android development related projects on Github. Few of the most popular are - Phonegap and Nativescript. These two projects make use of simple Javascript framework to develop android apps. Installation is not difficult and you just have to follow the instruction in the document.
There are few other projects such as Tabris, NodeJS Android etc that you can take a look at.

HTML5 - Though you may be surprised that how can a webpage markup is capable of creating apps for Android. The answer is simple. HTML5 based apps for android are mostly focused on apps which are dependent on web. So there are frameworks developed for android that makes use of HTML5. Few projects that are into this are - Cordova, Sencha, Ionic and Phonegap. Each of these frameworks have different way of installation and usage.

In order to develop the app you have to follow this mode of direction.

1. Install Java SDK
2. Install Android SDK
3. Download language specific port (e.g. phonegap or ionic etc)
4. Write the code.
5. Convert your code using native launcher scripts

This should be the direction in which you should be developing the app for Android.

Most of the frameworks mentioned in this answer are supported on all the operating system. You can download them on your operating system and start developing the app.

Android is an Operating system designed for portable system. It's purpose is to make sure that user can interface with the device and get his tasks done.

Android operating system Is primarily based on Java programming language. The Java language is used with Android Software Development Kit. However, there are many othe languages used along with Java.
There are several Android programmes written in C and C++ languages. These applications are developed using Android NDK- Native Development Kit.
Corona SDK is a third party SDK used for building graphics applications using Lua language. Lua is layered on top of C++ and OpenGL.
Delphi uses Object Pascal programming language for developing Android based apps. Lazarus too is used to develop Android app based on Object Pascal language.
Python has been in wider usage for developing multi touch application software. The Python library is sourced from Kivy.

Qt applications are De eloped using C++ and QML languages. Qt is in fact a multi platform development software. It uses both ADK and NDK.
Ruby is another language that is used to develop Android applications. Commonly used tool chain for the purpose is RubyMotion.
Xamarin is another C# code base. It is a cross platform tool that can be used to develop apps for iOS, Android and Windows.