Android Four components

one of the four components: Activity

activity life cycle: Create-to-run (visible actionable): onCreate () OnStart () Onresume ( )

Run-to-destroy (off): OnPause () onStop () OnDestroy ()

Run-stop (invisible and not operable): OnPause () onStop ()

Stop--run Onrestart () OnStart () Onresume ()

Run-to-pause (visible not operable) OnPause ()

Pause-to-run Onresume ()

1.activity creates three main elements: a: Declaring a class inheriting activity B: Associating layout C: Declaring package name in manifest, class name

Jump between 2.Activity (intention): startactivity (Intent);

3.A receives the message returned by the B interface and processes it: the Onactivityresult () method must be rewritten upon receipt (judging the returned content based on the request code and the result code)

4. Button click event: OnClick = "BTN"

In layout: public void btn (View v) {}

two of the four components:

Service Services

1. Service Open: StartService (); Service closed: StopService

2. Binding and unbinding of services: Bindservice (); Unbindservicce ();

Three of the four components:

Broadcastrecevice Broadcast recipient

1. There are two ways to register a broadcast receiver: A: List registration B: Code registration

Difference: A broadcasts can be received regardless of whether the application executes as long as the conditions are met, and B can be received only when the app is running and the conditions are the same.

Filter conditions:

Checklist: Permissions: Receive_sms condition: <cation ... "Android.provider.Telephony.SMS_RECEIVED"/>

Code: Permissions: receive_sms Condition: registerreceiver (Receiver,filter);

Receiver for matching broadcast

Filter for filtering conditions

When you register a broadcast using code, you must unregisterreceiver

Four components:

Content Provider Contents Provider

Android Four components