There are some ways to instantiate and pass data to fragments in android development. However, you must be careful when you do that and you should avoid the wrong approaches while you are instantiating and passing data to fragments.
The most recommended way of instantiate fragments with arguments is to have factory methods for this task.
Also, another important topic is about how to pass data to the fragments while instantiating them. In this case it is tempting to directly access the fields of your fragment and assign their values. However, this is the wrong approach. Because when your application send back to background and the other applications require more and more memory then your application and its resources will be cleared from the memory to open up space to the new ones.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| package com.gunhansancar.android.fragments; | |
| import android.os.Bundle; | |
| import android.support.v4.app.Fragment; | |
| import android.view.LayoutInflater; | |
| import android.view.View; | |
| import android.view.ViewGroup; | |
| import android.widget.TextView; | |
| /** | |
| * Sample fragment to demonstrate the instantiation of fragments with arguments | |
| * | |
| * Created by Günhan on 28.10.2015. | |
| */ | |
| public class MyFragment extends Fragment { | |
| private String name; | |
| private int age; | |
| private TextView mNameTextView; | |
| private TextView mAgeTextView; | |
| public static MyFragment newInstance(String name, int age) { | |
| Bundle bundle = new Bundle(); | |
| bundle.putString("name", name); | |
| bundle.putInt("age", age); | |
| MyFragment fragment = new MyFragment(); | |
| fragment.setArguments(bundle); | |
| return fragment; | |
| } | |
| private void readBundle(Bundle bundle) { | |
| if (bundle != null) { | |
| name = bundle.getString("name"); | |
| age = bundle.getInt("age"); | |
| } | |
| } | |
| @Override | |
| public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { | |
| View view = inflater.inflate(R.layout.fragment_sample, container, false); | |
| mNameTextView = (TextView) view.findViewById(R.id.nameTextView); | |
| mAgeTextView = (TextView) view.findViewById(R.id.ageTextView); | |
| readBundle(getArguments()); | |
| mNameTextView.setText(String.format("Name: %s", name)); | |
| mAgeTextView.setText(String.format("Age: %d", age)); | |
| return view; | |
| } | |
| } |
In this example, to instantiate MyFragment you need to call;
Fragment fragment = MyFragment.newInstance("Gunhan", 28);
If android decides to recreate your activity and fragment, it is going to call no-argument constructor and the system guarantees to pass the arguments bundle to it.
After that when you want to return to your application the android system will create your activity and also your fragment with the default constructor with the passed arguments bundle.
Therefore if you directly set your fields then you are gonna lose their values after recreate operation.
Update: How to use the newly instantiated Fragment in your activity?
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| FragmentManager fragmentManager = getFragmentManager(); | |
| FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); | |
| Fragment fragment = MyFragment.newInstance("Gunhan", 28); | |
| fragmentTransaction.add(R.id.fragment_container, fragment); | |
| fragmentTransaction.commit(); |
UPDATE 2: DEMONSTRATING HOW TO INSTANTIATE FRAGMENT IN FRAGMENT PAGER ADAPTER
You can find the example project on https://github.com/gunhansancar/FragmentPagerExample
Leave a Reply