Toggle Button is a special button that has two states for eg :"on" and "off".It can be an alternative to Radio Buttons. Method to create a Custom Toggle Button is given below :
Android is a true multitasking operating system . Android decides that it has sufficient resources it will maintain the app in a background state that can be brought quickly back to the foreground (for example, by clicking on the app's icon, or clicking the Back button---the curved back arrow---on the device). Many phones facilitate multitasking by making it easy to find the applications that have most recently been executing in the foreground.
Intents, Resources(such as strings and graphics), Notification signalings(light,sound,dialog), are also part of the components.
All these components play different role in the overall application and each one can be activated individually.
Activities : An activity represents a single screen with a user interface.Suppose if there is a listview and if clicking on each row it traverse to another page ,then the screen showing listview is an activity and the next page is another activity,where each one is independent of the others. An activity is implemented as a subclass of Activity ,that why we use
Services : A service is a component that runs in the background to perform long-running operations or to perform work for remote processes. A service does not provide a user interface.For example : Running an alarm in background A service is implemented as a subclass of Service. Content providers : They manages a shared set of application data.Data can be stored in SQLite Database,File systems,web or any other medium where application can access. Content Providers allows to modify and use these stored data.For example : storing users contacts details,where proper permission one can get the contacts. A content provider is implemented as a subclass of ContentProvider. Broadcast receivers : They responds to systems broadcast announcements.Some of the native Broadcast are volume control, light, switch on and off, screen on and off,bluetooth etc.A broadcast receiver is just a "gateway" to other components and is intended to do a very minimal amount of work. For instance, it might initiate a service to perform some work based on the event. A broadcast receiver is implemented as a subclass of BroadcastReceiver. Who Activates A component ? The above components are activated by a message called Intents. Intents bind individual components to each other at runtime, whether the component belongs to your application or another. An intent is created with an Intent object, which defines a message to activate either a specific component or a specific type of component—an intent can be either explicit or implicit, respectively.
What is a Content Resolver ?
The Content Provider, is not activated by intents. It is activated when there is request from ContentResolver. These Resolvers handles direct transaction with the providers so they donot need further any method calls. This leaves a layer of abstraction between the content provider and the component requesting information (for security). What is an AndroidManifest file ? This is a root directory of Android application where all the components are declared.Other than this they also have
user permissions the application requires, such as read and write external storage
Declare the minimum API level
Declare hardware and software features such as bluetooth or a printer
