Question

1. When receiving a result from another Activity, which method must be overridden? Explain the meaning of the parameters to this method.

2. During which Activity lifecycle method should you save any state in your application?

3. What is the difference between an explicit Intent and an implicit Intent?

4. Explain what happens when you try to start an Activity using an implicit Intent?

5. List the Activity lifecycle events in order, for the following situation. Activity 1 is already in

   the the created state (onCreate has already been called).

   1. A button in Activity 1 is pressed, launching Activity 2

   2. Once Activity 2 has become visible, the user presses the back button.

   3. Activity 1 is displayed and the user presses the back button again.

Answer 1

1.OnCreate(),Onstart() ,Onresume(),OnsaveInstance state()-In this state activity life cycle changes the states,
ex-When a configuration change occurs, the activity is destroyed and recreated. The original activity instance will have the onPause(), onStop(), and onDestroy() callbacks triggered.
A new instance of the activity will be created and have the onCreate(), onStart(), and onResume() callbacks triggered.
Use a combination of ViewModels, the onSaveInstanceState() method preserve an activity’s UI state across configuration changes,and its combining these options depends on the complexity
of your UI data, use cases for your app, and consideration of speed of retrieval versus memory usage.

2-explicit vs implicit intend

Explicit intent is an intent that is publicly stated and its made available for the participants and
Implicit intent is an intent that is not publicly stated.To use an implicit intent, create an Intent object as you did for an explicit intent, only without the specific component name.
implicit Intents do not directly specify the Android components which should be called, it only specifies action to be performed and by using Uri can be used with the implicit intent to specify the data type.
Explicit intents are used in the application itself where in one activity it can switch to other activity,can also be used to
pass data to other activity using putExtra method and retrieved by target activity .

3-Such implicit Intents are used when you don't explicitly know which Activity has to be started and you want the Android system to decide which component to start.If the system finds multiple components which can handle handle your Intent, it will allow the user to choose.
Implicit intents are used when you want start an activity in another application simply by specifying the type of action you want to perform, When we pass an implicit intent,
the Android system resolves the intent to an app that can handle the intent and starts that app's

4.List of activity life cylce occures and activiy 1 is alraedy in use and now launching activity 2 ,once activity 2 is visble the use press back button then ---Start Activity2 with startActivityForResult and use setResult method for sending data back from Activity2 to Activity1. In Activity1 you will need to override onActivityResult for updating TextView with EditText data from Activity2, and in the activity 1 user again click on back button.