I have 2 Fragments - ButtonFragment and ListViewFragment - in my Activity MainActivity.
ButtonFragment contains a Button, ListViewFragment contains a ListView.
Each time I click on the ButtonFragment Button I want the ListViewFragment to show/hide.
How do I code this properly?
Currently my code looks like this:
MainActivity.java
public class MainActivity extends Activity implements Communicator {
ButtonFragment buttonFrag;
ListViewFragment listviewFrag;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonFrag= new ButtonFragment();
listviewFrag = new ListViewFragment();
manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.add(R.id.button_fragment, buttonFrag, "Fragment1");
transaction.add(R.id.listview_fragment, listviewFrag, "Fragment2");
transaction.commit();
}
}
ButtonFragment.java
public class DynamicButtonsFragment extends Fragment implements View.OnClickListener {
Button btn;
#Override
public View onCreateView(LayoutInflater inflater,
#Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.button_fragment_layout, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
#Override
public void onClick(View v) {
//?? hide listview fragment from here ??
}
}
ListViewFragment.java
public class ListViewFragment1 extends Fragment {
protected ArrayAdapter<String> adapter1;
#Override
public View onCreateView(LayoutInflater inflater,
#Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.list_view_fragment, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
}
So my question is where do I implement the showing/hiding of ListViewFragment? I feel like I should send data to the MainActivity through the onClick method of ButtonFragment. But I do not know how to do so.
Or do I only add code in the MainActivity since the MainActivity has access to all the Fragments?
I am having trouble becase the Button is in a Fragment, not part of the MainActivity. I haven't really seen cases like this...
Can someone please help?
You cannot show/hide a Fragment directly. You may show/hide a UI object like Listview. If you like, you can show/hide Fragment indirectly by using the FragmentTransaction, and you can call its method add, remove or replace.
A link for sample code is Fragments
Do this ..
android.app.Fragment fragment = getActivity().getFragmentManager().findFragmentByTag("YOUR_FRAGMENT_TAG");
getActivity().getFragmentManager().beginTransaction().hide(fragment);
inside your click event!
One more thing when you add fragments like this..
transaction.add(R.id.button_fragment, buttonFrag, "Fragment1");
transaction.add(R.id.listview_fragment, listviewFrag, "Fragment2");
you're expected to provide the container id instead of the id of the fragment.
Example: For MainActivity container use R.id.containerMain
If you in fragment want to do some MainActivity function , you can try
#Override
public void onClick(View v) {
//?? hide listview fragment from here ??
((MainActivity)getActivity()).hidelistView();
//hidelistView you should imp in your MainActivity
}
If you have fragments within the same layout, you can use the following code:
http://www.java2s.com/Code/Android/Core-Class/Demonstrationofhidingandshowingfragments.htm
If not, than you can use several possibilities...
You can use an Intent to send data to MainActivity.
You can have a singleton instance where you store pointer to your MainActivity.
You can also use Handler to send messages, but the ways discribed above are easier to implement and should be enough for you.
Related
Unlike typical android projects starting with MainActivity with all the code of the layout object in it. This architecture requires me to have the initial code in a custom object. Here's a structure for better understanding.
java/MainActivity.java
java/User.java
layout/activity_main.xml
layout/user.xml
Now I also need a reference to User object within MainActivity and it looks like this.
public class MainActivity extends AppCompatActivity {
public Users users; // instantiate custom class and show
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
My User class looks like this.
public class User extends AppCompatActivity {
ListView userList;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.user_list, container, false); // Inflate the layout for this fragment
userList = view.findViewById(R.id.userList);
return view;
}
}
layout/user.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="org.puremvc.java.demos.android.employeeadmin.view.components.UserList">
<ListView
android:id="#+id/userList"
android:layout_width="395dp"
android:layout_height="715dp"
tools:layout_editor_absoluteX="8dp"
tools:layout_editor_absoluteY="8dp" />
</FrameLayout>
So, in other words, MainActivity just acts like a stage doing nothing except just providing a reference to the Initial object. Now I do need MainActivity to be there, can't point User to be a launcher in the manifest. Responsibilities are to be taken care of by User class.
Question: How to instantiate CustomClass User and show.
Context: The MainActivity class has to be minimalistic and clean, no User related code (ListView), all logic lies in the custom class.
P.S. There can be lateral approaches, as long as I have a reference to user Object in MainActivity and it's displayed on launch, I'll accept the answer.
As per my understanding: there should be two approaches.
First, by using the Fragment inside your Activity. Write all initialize and data flow codes inside the fragment and just initialize and start the fragment from the Activity. So when the Activity will start, it will give all its tasks to the fragment with its Context and rest thing Fragment will do.
Like below:
public class MainActivity extends AppCompatActivity {
public Users users; // instantiate custom class and show
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//the fragment stuff
FragmentManager fm= getFragmentManager() //or get SupportFragmentManager when the Fragment comes from Support lib
FragmentTransaction ft= fm.beginTransaction();
Fragment fragment= new UserListFragment();
ft.add(R.id.fragment_container, fragment);
ft.commit();
}
}
OR, the second approach should by using Interface and communicate both Activity and the Custom Class (or you can call it Controller) with it.
Its nothing, but a simple MVC design pattern which I never recommend.
You can write one Interface like below:
public interface IController{
public void initialize(Activity activity, Bundle savedInstanceState);
public void engage();
public void disengage();
}
Then, make an instance of this Controller inside your Activity/BaseActivity and use like below:
public MainActivity(IController controller){
this.controller = controller;
}
Then call each callback methods from their appropriate place to make them work inside the Controller.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//give the priviledge of onCreate to initialize
controller.initialize(this, savedInstanceState);
}
Then in your Controller class, just write the same program which you supposed to write inside Activity:
public class Your_Controller implements IController {
#Override
public void initialize(Activity activity, Bundle savedInstanceState) {
//do super where needed
//make one class level Activity instance to work in other methods
act = activity;
//just initialize views like below
TextView tv = (TextView) activity.findViewById(R.id.abc);
}
I'm new Android programming. Earlier I was working with activities, where i could implement onClick on an ImageButton and go to a different activity.
Now I need to do the same but using Fragments. I have a prototype with a menu that always appear on screen and can show different activities to the user. The different lactivities would be inside this container.
Now I want to place an ImageButton inside a fragment and make that the screen shows the next fragment. But I'm confused how to do it.
I have the following components:
Activity_main(java)+activity_main.xml (with menu)
Fragment1(java)+fragment1.xml(working normal)
Inside this layout I have an ImageButton and want to show Fragment2
Fragment2(java)+fragment2.xml
How should look Fragment1 to can call Fragment2?
I will be glad if the answer could be the clearest possible because I'm new on it, and maybe I could forgot an obvious step. Thanks
Simply make a method in your activity which will always change/replace fragment when you invoke it. something like
public void updateFragment(Fragment fragment){
//add fragment replacing code here
}
in your fragment, invoke it some thing like this
((YourActivity)getActivity()).updateFragment(new YourFragment());
since, it is just an idea which works fine but still you can improve the logic.
Actually, going from one fragment to another is almost similar to going from one activity to another. There are just a few extra lines of code.
First, add a new Java class named SingleFragmentActivity which would contain the following code-
public abstract class SingleFragmentActivity extends AppCompatActivity
{
protected abstract Fragment createFragment();
#LayoutRes
protected int getLayoutResId()
{
return R.layout.activity_fragment;
}
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(getLayoutResId());
FragmentManager fm = getSupportFragmentManager();
Fragment fragment = fm.findFragmentById(R.id.fragment_container);
if (fragment == null)
{
fragment = createFragment();
fm.beginTransaction().add(R.id.fragment_container, fragment).commit();
}
}
}
Make your activities in the following format-
public class SomeActivity extends SingleFragmentActivity
{
#Override
protected Fragment createFragment()
{
return SomeFragment.newInstance();
}
}
And your fragments like this-
public class SomeFragment extends Fragment
{
public static SomeFragment newInstance()
{
return new SomeFragment();
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View v = inflater.inflate(R.layout.fragment_some, container, false);
return v;
}
}
After this everything has the same code as you have for activities except for one small detail which is your onCreateView(LayoutInflater, ViewGroup, Bundle) class. This is how you would write it-
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View v = inflater.inflate(R.layout.fragment_some, container, false);
mTextView = (TextView)v.findViewById(R.id.some_text);
mButton = (Button)v.findViewById(R.id.some_button);
mTextView.setOnClickListener(new View.OnClickListener()
{
#Override
public void onClick(View v)
{
check();
}
});
return v;
}
And that is it!
Hi i hope you are already aware about the fragments and their uses but still here is a brief. They are child to an activity and an activity can have more than one fragment so you can update your layout without changing activity just by changing fragments.
You can found more on fragment here : https://developer.android.com/training/basics/fragments/index.html
Back to the original problem, supposed you are in MainActivity.java and you want to load fragment in it, so you do this to load fragment first time.
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.frame, new Fragment1);
transaction.addToBackStack(null);
transaction.commit();
You will need this method to change fragment from another fragment, so add this in your MainActivity
public void changeFragment(Fragment fragment){
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.frame, new Fragment1);
transaction.addToBackStack(null);
transaction.commit();
}
Now from a button click in this fragment
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((MainActivity)getActivity()).changeFragment(new Fragment2);
}
});
Hope it will help!
Users have a crash. I know why but I do not know how to fix it. I am newbie in android dev.
Situation:
Android: Fragment inside Activity. Fragment has an EditText. Activity has a button. User tap the button. Inside Button.OnClick() I want to get text Fragment.EditText.getText();
Some users have a crash here EditText.getText(). i.e. EditText is null.
How I do:
In Activity:
public class MyAcrivity extends AppCompatActivity implements OnFragmentInteractionListener {
final MyFrag myFrag= MyFrag.newInstance();
public void run(final View view) {
//some users have crash here because getEt() return null
final String str = myFrag.getEt().getText().toString();
}
}
In Fragment:
public class MyFrag extends Fragment {
private EditText et;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_myfrag, container, false);
et = (EditText) view.findViewById(R.id.et);
return view;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
et = (EditText) view.findViewById(R.id.et);
}
public EditText getEt() {
// return (EditText) getView().findViewById(R.id.et); here getView() could be nul too
return et;
}
}
I know getView() could be null (already googled it).
Init "View" inside onCreateView useless. Crash still happend.
Init "View" inside onViewCreated useless. Crash still happend.
I can NOT reproduce this crash in emulator or my smartphone. I have stable work of my app. BUT some users have the crash and Fabric(crashlytics) is sending messages about it.
People! Help! How to obtain some View from Fragment correctly? I can not to find answers from lifecycle of Fragment. Please explain to me what is wrong.
From your code it seems you have only created instance of fragment and trying to access the view .But to get the view of the fragment you have to add fragment to your activity.
Do this in your activity
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
MyFrag myFrag= MyFrag();
ft.replace("YOUR_FRAGMENT_CONTAINER's id", myFrag);
ft.commit();
Just a hunge, try to do the newInstance() call in the activity lifecycle. Otherwise, there might not be a trustable context to attach fragments. Try to do so in the onCreate().
And something that might be unrelated, but did you properly attach that fragment to the activity? Chances are you are already doing, since some users are correctly accessing it. Anyway, here's the fragment documentation, and a code block to attach it.
FragmentManager fragmentManager = getFragmentManager()
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Fragment myFrag = MyFrag.newInstance();
fragmentTransaction.add(R.id.fragment_container, myFrag);
fragmentTransaction.commit();
Use butterknife like this:
class ExampleActivity extends Activity {
#Bind(R.id.user) EditText username;
#Bind(R.id.pass) EditText password;
#BindString(R.string.login_error)
String loginErrorMessage;
#OnClick(R.id.submit) void submit() {
// TODO call server...
}
#Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_activity);
ButterKnife.bind(this);
// TODO Use fields...
}
}
Add the fragment to the Activity in Activity.onCreate() method.
Get the reference to the Activity during Fragment.onAttach (Context) in the Fragment.
Create a method in Activity like enableButton(), which will enable the button like button.setEnabled (true).
Call this method from Fragment onCreateView after initializing the EditText.
This way you can ensure that EditText is initialized before the button is clicked.
Also remember to make the Activity reference null in Fragment.onDetach() to prevent any leak.
If you use getActivity.findViewById in Fragment.
public class MyFrag extends Fragment {
private EditText et;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_myfrag, container, false);
return view;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
et = (EditText) getActivity.findViewById(R.id.et);
}
public EditText getEt() {
// return (EditText) getView().findViewById(R.id.et); here getView() could be nul too
return et;
}
}
I have created a MainActivity which consists of 3 tabs which are scrollable (by using ViewPager). Now each of these 3 tabs is a Fragment. Also, I am using ActionBarSherlock (ABS).
For the 1st Fragment, I have created the following class:
public class Fragment_1 extends SherlockFragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v = inflater.inflate(R.layout.fragment1, container, false);
return v;
/* R.layout.fragment1 only contains a TextView. */
}
}
For the 2nd Fragment, I want to extend a FragmentActivity as shown below.
public class Fragment_2 extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment2);
}
}
The 3rd Fragment is same as the first one.
But when I launch the app, it crashes. So, am I wrong in extending FragmentActivity for the class Fragment_2? Is it illegal to extend a FragmentActivity or even an Activity to fragment classes? If not, what is the problem here?
Thanks.
EDIT: After #CommonsWare's answer I updated my class as follows:
public class Fragment_2 extends SherlockFragment {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Button send = (Button) findViewById(R.id.bSend); //Error at this line
//some error free code
FragmentTransaction t = getSupportFragmentManager().beginTransaction(); //Error at this line
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v = inflater.inflate(R.layout.fragment2, container, false);
return v;
}
My final two questions are:
How should I access my R.id.bSend Button in the Fragment_2 class.
Eclipse is giving the suggestion to change getSupportFragmentManager() to getFragmentManager(). Is that change all right?
Thanks!
Is it illegal to extend a FragmentActivity or even an Activity to fragment classes?
Fragment is a Java class. Your fragment implementations (for use as pages in your ViewPager) must inherit from Fragment, directly or indirectly.
Activity does not inherit from Fragment. FragmentActivity does not inherit from Fragment. Hence, you cannot inherit from Activity or FragmentActivity and somehow also inherit from Fragment.
Let's say I have this button:
<Button
android:id="#+id/idone"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="D2"
android:onClick="myMeth"/>
I have several times used this to call methods from a layout xml as it calls the method from the activity that inflated such view.
Recently with DialogFragments, well it does not work at all. I keep getting an error telling me that such method does not exist. Where is it then looking for such method? I have added it to the DialogFragment class:
public class myActivity extends DialogFragment {
public DiceDialog() {
// empty constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.myDialog, container);
getDialog().setTitle("Hello");
return view;
}
public void myMeth(View view) {
//...
}
As well as in the activity that instantiates the FragmentManager and calls the dialog:
public Class MainActiviry Extends FragmentActivity {
//...
public void onCreate(Bundle savedInstanceState) {
// ..
FragmentManager fm = getSupportFragmentManager();
MyActivity dialog = new AddDiceDialog();
dialog.show(fm, "tag");
}
public void myMeth(View view){
//...
}
And still the messag is that MyMeth is not found.
I have already read that using interfaces and listeners is the correct way to communicate between activity and dialog fragments, but what I am trying to figure out here is where that myMeth call is being made, because well,it is called.
You can implement public myMeth(View view) in your Activity, which will then check for the currently visible Fragment, and call its method.
If you want to use more then one callable method in your Fragment, you can utilize the id's of the calling views and implement a switch, calling a different fragment method according to the id of the View.