Android Development Basics

All elements in the layout are built using a hierarchy of View and ViewGroup objects.

Widgets are individual UI elements like buttons, text views, and image views.

Declare UI elements in XML using the Android XML syntax found in the Android namespace.

Instantiate layout elements at runtime using the findViewById() method inside the Activity class.

Density-independent pixels (dp) are the preferred unit for screen dimensions to ensure consistency across different devices.

Complex controls that are used to display and interact with data in a structured way.

An abstract class that serves as the base for various list-like controls, such as ListView, GridView, and Spinner.

Classes that simplify the process of connecting data (like arrays, lists, or database results) to complex visual controls.

A standard adapter for displaying data from an array or ArrayList in a ListView.

Used to connect data from a database cursor (which represents a set of database records) to a ListView or GridView.

An event that is triggered when a user selects an item from a list or similar view.

A method that handles user interactions with a view, like a tap on a list item.

A mechanism that allows data to be saved and restored in a way that allows it to be transferred between different parts of an app (like between different activities) or even across different devices.

An operation that is performed independently of the main thread, typically involving time-consuming tasks.

A lightweight thread of execution that manages communication between the main thread and background threads.

The state where an Android app fails to respond to user inputs within a specific time limit, often caused by long-running tasks on the main thread.

A mechanism to execute code asynchronously, providing an interface to submit tasks to a pool of threads for execution.

The process of accessing data from a remote server, often involving HTTP requests and responses.

A class that encapsulates the core functionality of an Android application.

A container for data passed between activities, services, and other application components.

An abstract class in Android that allows you to perform long-running operations on a background thread and publish results to the UI thread.

The first method called in an AsyncTask, executed on the UI thread before the background task starts. Useful for initializing UI elements or displaying a progress dialog.

A method called when an activity is created. It is responsible for initializing the activity and setting up its user interface.

This method runs on a background thread and performs the long-running operations. You can use it to download data, process images, or perform any time-consuming task outside the main thread.

A method called when an activity is resumed after being paused. It is used to restore any state that was saved during onPause().

Called on the UI thread to update the progress of the background task. This method can be called multiple times during the doInBackground() method.

A method called when an activity is paused. It is used to save any state that needs to be preserved if the activity is destroyed.

A method called when an activity is stopped. It is used to release any resources that are no longer needed.

This method is called on the UI thread after the doInBackground() method completes. It receives the result from the background task and updates the UI accordingly.

A method that allows you to publish updates from the background thread to the UI thread. It triggers the onProgressUpdate() method.

A method called when an activity is destroyed. It is used to clean up any resources that were allocated during the activity's lifetime.

A method that allows you to save the state of an activity using a Bundle object. This is important because if the activity is destroyed and recreated later, it can be restored to its previous state.

The method used to execute an AsyncTask, starting the background operation. It's called on the UI thread.

A method that allows you to restore the state of an activity from a Bundle object. This is called when the activity is recreated after being destroyed.

AsyncTask doesn't accept primitive types like int or boolean; you must wrap them in corresponding object types such as Integer or Boolean.

To start an activity, you need to provide a context and an Intent containing information about the activity you want to start.

This intent type designates the action to be performed or the type of data to be considered (e.g., 'view,' 'edit', 'send').

This intent type describes the type of action you want to perform, leaving the system to choose the best activity to handle it.

Components of an Intent that provide additional information about the requested action. These include data, categories, and extras.

A method that allows you to start an activity and receive a result back from it.

A class that represents the global context of an application. It provides access to resources, system services, and other application-related information.

A layout that arranges its child views in a single row, either horizontally or vertically. It automatically adds scrollbars if the content exceeds the screen size.

A property used within LinearLayout to distribute remaining space among child views according to their assigned weights. Higher weight means a view takes up more space.

A layout that manages a single visual element. Child views are positioned implicitly in the top-left corner, and can overlap. Alignment is controlled using android:layout_gravity.

A layout that allows content to be scrolled. Can be used with a FrameLayout to provide scrolling for a single view. Uses scrollbars and can fill the entire available view.

A layout that organizes content into rows and columns. Rows are defined using TableRow, and columns are associated with each view using android:layout_column. The layout_span attribute allows a view to span multiple columns, and shrinkColumns, stretchColumns, and collapseColumns control how columns handle available space.

A layout that positions child views relative to each other or to the parent view. You can specify how a view should be aligned to the left, right, top, bottom, or center of another view or the parent.

Specifies the alignment of a view within its parent. It applies to views within LinearLayout as well as views within a FrameLayout.

Used within LinearLayout to control the alignment of child views based on their position within the parent, options include 'center_vertical', 'center_horizontal', 'top', 'bottom', 'left', and 'right'.