Android Fragments

 

Android Fragments

Android fragments is a class implementing a segment of an activity in simple words we can say that Android Fragments is a part of an activity. Actually, Android Fragments don’t subclass the Context class. The Android Fragments class doesn’t extend the Activity class or implement the Context class . The Android fragments case is connected with an activity case. Regularly you get in this technique a reference to the activity which utilizes the fragment for further introduction work. Fragments were initially introduced in Android 3.0 for the better experience in.  It helps to organize UI components. The Android Fragments lifecycle is fundamentally the same as the Activity life-cycle. We have explained the Android Fragments life cycle in this tutorial.

android fragments

Android Fragment Main Points

These are the eight main points of Android Fragment

  • An Android fragments ha its own format and its own behavior with its life-cycle callbacks.
  • You can include or expel fragments in an activity at any time while the activity is running.
  • You can combine numerous fragments in a solitary activity to build a multi-plane UI.
  • A fragment can be utilized as a part of numerous activities.
  • life-cycle is firmly identified with the life cycle of its host activity which implies when the activity is delayed, every one of the fragments accessible in the activity will likewise be stopped.
  • A fragment can implement a behavior that has no UI segment.
  • Fragments were added to the Android API in Honeycomb version of Android which API  11.
  • You make fragments by developing Fragment class and You can insert a fragment into your activity format/layout by announcing the fragment in the activity’s layout file, with  <fragment> tag.

Preceding fragment presentation, we had an impediment since we can represent just a solitary activity on the screen at one given point in time. So we were not ready to partition device screen and control distinctive parts independently. Be that as it may, with the presentation of fragment we got more adaptability and neglect the impediment of having a solitary activity on the screen at once. Presently we can have a solitary activity yet every activity can contain multiple fragments which will have their own particular layout, events  and finish life cycle.

Following is the simple example of how two User interface modules characterized by fragments can be joined into one activity for a tablet design, however, isolated for a handset design.

android fragments

Usually, The application can install two fragments in Activity A when running on a tablet-sized device. Be that as it may, on a handset-sized screen, there’s insufficient space for both fragments, so Activity An incorporates just the part for the list of articles, and when the client chooses an article, it begins Activity B, which incorporates the second fragment to read the article.

Android Fragment Life Cycle

As we mentioned above that Android fragment has its own life cycle but it is very similar to an android activity. We will explain that how it is similar to an android activity . We included a pic of fragment lifecycle which shows different stages of its life cycle

android fragments

Here is the list of methods to explain the above diagram −

  • onAttach() – The fragment occasion is connected with an activity instance.The fragment and the activity are not completely unstated. Commonly you get in this method a reference to the activity which utilizes the fragment for further initialization work.
  • onCreate() – The framework calls this method while making the fragment. You ought to introduce fundamental parts of the fragment that you need to hold when the fragment is delayed/pause or stopped, then continued.
  • onCreateView() – The framework calls this callback when it’s the ideal opportunity for the fragment to create its UI for the first time. To draw a UI for your fragment, you should give back a View segment from this method that is the root of your fragment’s layout. You can return invalid if the fragment does not give a UI.
  • onActivityCreated() – The onActivityCreated() is called after the onCreateView() method when the host activity is made. Activity and fragment instance have been made and in addition the perspective chain of an importance of the activity. Now, view can be gotten to with the findViewById() method. illustration. In this strategy, you can instantiate objects which require a Context object
  • onStart() – The onStart() – technique is called once the fragment gets visible and working.
  • onResume() – Fragment gets to be dynamic and active.
  • onPause() The framework calls this method as the main sign that the client is leaving the fragment. This is normally where you ought to confer any changes that should be persevered past the present client session.
  • onStop() – Fragment going to be stopped by calling onStop()
  • onDestroyView() – The view  Fragment will destroy if we use this method
  • onDestroy() – this method  called to do last clean up of the fragment’s state however Not ensured to be called by the Android platform.

How to use Android Fragments?

In this segment, I will teach You how to use android fragments to create UIs. This article gives information about the using of Fragments to build User Interfaces in Android applications. Here are the steps. Just follow these steps

  • As a matter of first importance choose what number of fragments you need to use in an activity. For instance how about we need to use two fragments to handle portrait and landscape methods of the device.
  • Next, in view of a number of fragments, make classes which will expand the Fragment class. The Fragment class has previously mentioned callback functions. You can supersede any of the functions in view of your prerequisites.
  • Comparing to every fragment, you should make format documents in the XML file. These files will have a layout for the characterized fragments.
  • At long last alter activity file to characterize the real logic of replacing fragments in view of your necessity.

Types of Android Fragments

Fundamentally fragments are separated as three phases as demonstrated as follows.

  • Single frame fragments − Single frame fragments are utilizing for hand hold gadgets like mobiles, here we can demonstrate stand out fragment as a perspective.
  • List fragments − fragments having exceptional list perspective is called as list fragment
  • Fragments transaction − Using with fragment transaction. we can move easily one fragment to another fragment.