Introduction First of all, a distinction should be made between the terms: “database”, “database management system” (so-calledDBMS “Database Management System”) and the “SQL language” itself. “Relational database” is a digital database based on the relational data model and is a set of related data that replaces some aspect of the real world. “Relational Database Management … Read more
LiveData class LiveData
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public abstract class LiveData extends Object |
LiveData is an abstract class called observable data holder in charge of keeping information about the data and notifying all interested observers if changes occur. LiveData is actually just an Abstract Class. So it can’t be used as itself. The most important feature of LiveData is that it is aware of … Read more
MVVM pattern MVVM (Model-View-ViewModel) is a pattern that separates an application into multiple components so that each component has its own specific responsibilities. When using the MVVM pattern, the “code” of the application is separated into three parts: View, ViewModel and Model, this architecture is recommended by Google as one of the best ways to … Read more
What is ViewPager? ViewPager is a Layout Manager that allows the user to move through pages of data with movements to the left or right, while when changing pages, a built-in animation is executed. Most often, those pages with data are fragments, although they can be something else, for example. images that slide… ViewPager is … Read more
Introduction The adapter is a bridge between the data source (Array object, List object…) and the user interface. The role of the adapter object (implements the Adapter interface) is to read data from various data sources, and based on them fills View objects with members of a ViewGroup. So far we have used ListView, but … Read more
Introduction In the basic version of the adapter, only one String data is used, which is placed in one of the predefined android layouts with one TextView. Custom adapter differs from “ordinary” in that one list element is presented with more data and it is necessary to define a “more complex layout” that would accept … Read more
Introduction Adapter is a bridge between the data source (Array object, List object…) and the user interface. The role of the adapter object (implements the Adapter interface) is to read data from different data sources, and based on them fill View objects members of a ViewGroup. ViewGroup: ListView, RecyclerView, GridView, Spinner, Gallery whose contents are … Read more
Introduction “Layout inflation” is a term used to describe the process by which an XML resource is parsed and converted into a View object. The activity has its own method setContentView() with which it inflates its root view: Example
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@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.neki_view); } |
But we can convert other layouts into a View object (thereby enabling the layout elements … Read more
Introduction A fragment is a modular part of an activity, which has its own life cycle, receives its own input events, you can add or remove it while the activity is running. A fragment unifies the View and logic so that it can be easily reused within one or more different activities. There can be … Read more
Introduction “Listener pattern” is one of the most commonly used patterns used in application development. The working principle is based on the fact that in one class we define an event and the moment when the execution of the event starts (“trigger event”), while in another class we define an object (so-called listener object) that … Read more
