10. Activity life cycle
10.1. States of an activity
An activity can be in different states depending how it is interacting with the user. These states are described by the following table.
9. Logging in Android
9.1. The log system of Android
The Android system uses a centralized system for all logs. The application programmer can also write custom log messages. The tooling to develop Android applications allows you to define filters for the log statements you are interested in.
8. Views and layout manager
8.1. View – The user interface widgets in Android
A view in Android represents a widget, e.g., a button, or a layout manager. The Android SDK provides standard views (widgets), e.g., via the Button, TextView, EditText classes. Additional libraries provide more complex widgets, for example, RecyclerView.
7. The Android Manifest.
The components, settings and metadata of an Android application are described in the AndroidManifest.xml file. This file is known as the manifest file or the manifest.
Android allows you to create static resources like images and XML configuration files. This allows you to keep these resources separate from the source code of your Android application.
4. The Android SDK Manager
Each version of Android has its own SDK (Software Development Kit) that enables you to create applications for the Android platform. Since you just went through the setup wizard, you’ll already have the latest version of the SDK available to you.
5. Conversion process from source code to Android application
The Java source files are converted to Java class files with the Java compiler. The android SDK contains a tool known as dx that converts Java class files into a .dex (Dalvik Executable) file. All class files of the application are placed in this .dex file. throughout this conversion process redundant information within the class files are optimized within the .dex file. as an example, if an equivalent String is found in numerous class files, the .dex file contains only one reference of this String.
5. How to develop Android Applications
Android applications are primarily written within the Java programming language.
During development the developer creates the android specific configuration files and writes the application logic within the Java programming language.