Build Your First Android App in Java: In our free, self-paced Android Developer Fundamentals training, you learn basic Android programming concepts using the Java programming language. You build a variety of apps, starting with Hello World and working your way up to apps that schedule jobs, update settings, and use Android Architecture Components. Each lesson includes a codelab with solution code in GitHub, concept documentation, and a slide deck.
Build Your First Android App in Java: In the Android Developer Fundamentals course, you learn basic Android programming concepts and build a variety of apps, using the Java programming language. You start with Hello World and work your way up to apps that schedule jobs, update settings, and use Android Architecture Components.
Not only is Java the official programming language for Android app development (along with Kotlin), Java itself is used by Google for large parts of the Android internals. There are two distinct parts to learn Java for writing an Android app. One is the Java programming language itself, the other is understanding how to create an app in terms of its user interface, the Android OS, and the Android Software Development Kit (SDK). In this tutorial we will deal with the first of these, the Java programming language.
To start to learn Java and write Java programs you need a way to compile source code and turn it into an executable for the Java runtime. The normal way to do this is to install the Java Development Kit. At the time of writing the current version of Java is Java 8, however it is relatively new, so Android uses Java 7. If you are unsure about installing the JDK then read this How to Install the Java Software Development Kit tutorial. Oracle also provides a JDK 7 Installation Guide.