Android and Java questions - answers @androidquestions-blog - Tumblr Blog

#examples

Loaders are best for monitoring data source and deliver new results to refresh UI. After configuration change no need to re-query the data

More on loaders http://www.androiddesignpatterns.com/2012/09/tutorial-loader-loadermanager.html

#loaders

#content providers #loaders

This is based on Android Studio version 0.8.14 and may be subject to change in future versions of Android Studio.

#gradle #android studio #libraries

#styles

How to save instance state in activity?

The onRestoreInstanceState() or the onCreate()methods can be used to recreate the instance scope of an activity if it is restarted.

Prefer using the onRestoreInstanceState() method for restoring the instance state. This approach separates the initial setup from restoring the state.

If the user interacts with an activity and presses the Back button or if the finish() method of an activity is called, the activity is removed from the current activity stack and recycled. In this case there is no instance state to save and the onSaveInstanceState() method is not called.

If the user interacts with an activity and presses the Home button, the activity instance state must be saved. The onSaveInstanceState() method is called.

If you override onSaveInstanceState() and onRestoreInstanceState() you should call the super implementation of it

#activity

When onDestroy() could be used?

onDestroy() will be called if you explicitly call finish() yourself.

Your main activity calls startActivityForResult() on a map activity.

Map activity with a LocationListener, the user clicks the map and selects say a local restaurant.

The activity then , sets up some extras to be sent back to your main activity, it then explicitly call's finish() on itself and in the onDestroy() kills the LocationListener and other variables you had invoked.

#activtiy

Which callback is quaranteed if activity leaves running state ?

onPause() is guaranteed to be called.

onStop() and onDestroy() is not guaranteed to be called.

All clean up should be done in onPause()

#activity

How to use LoacalBroadcastManager?

If we want to use observer pattern, we want to send broadcast within our app only we can use LocalBroadcastManager. http://developer.android.com/reference/android/support/v4/content/LocalBroadcastManager.html

http://stackoverflow.com/questions/8802157/how-to-use-localbroadcastmanager

#broadcast receivers #design patter

Android versions after Gingerbread(2.3)

Android 3 [Honeycomb] - this was major release

Support for fragments

better 3D

Android 4. [Ice Cream Sandwitch]

Android 4.1/4.2 [Jelly Bean]

Android 5 [Lollipop]

Songs, photos, apps can be enjoyed across multiple devices picking up where it was left off.

Material design.

#about android