Obviously, I am new to Android - XML programming... So I have a navigation drawer, and once item is selected from the drawer, a corresponding fragment on the right side will display. Inside that fragment, I have linear layouts. I'd like to get redirected to another activity once that linear layout has been tapped. I was able to make it work on activities, by using android:onClick on XML file, but can't make it work on fragment. Somebody help me please.
App interface, refer to this image:
http://i.stack.imgur.com/u6dHi.jpg
Code:
fragment_smart.xml - the display once item's selected. I am trying to use the onClick on xml.
<LinearLayout
android:id="#+id/linearLayoutsmart1"
android:layout_width="match_parent"
android:layout_height="30dp"
android:layout_below="#+id/smart_title"
android:layout_marginLeft="15dp"
android:layout_marginTop="15dp"
android:orientation="horizontal"
android:weightSum="1"
android:onClick="smart_recommended_link">
Here's my Java code:
public class FragmentSmart extends Fragment {
public static final String TAG = "stats";
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View myfragment = inflater.inflate(R.layout.fragment_smart, container, false);
return myfragment;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
public void smart_recommended_link(View view) {
Intent smartRecommendedIntent = new Intent(this, SmartRecommended.class);
startActivity(smartRecommendedIntent);
}
}
The app is crashing when I clicked on the linearlayout using this code. What's the best thing to do here? Thank you!
For fragments you need to add the listener programmatically:
public class MyFragment extends Fragment implements View.OnClickListener {
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
view.findViewById(R.id.my_layout).setOnClickListener(this);
}
#Override
public void onClick(View v) {
// Handle click based on v.getId()
}
}
First of all, linear layouts cant trigger onClick events by default.
Check this answer for more information: LinearLayout onClick.
You can get the LinearLayout from the view in your onCreateView() like this:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View myfragment = inflater.inflate(R.layout.fragment_smart, container, false);
LinearLayout layout = (LinearLayout)myFragment.findViewById(R.id.linearLayoutsmart1);
// here you can set a listener of any type you want to the layout
return myfragment;
}
In fragments, you must use getActivity() method instead of this to reference the activity that the fragment is attached to.
public void smart_recommended_link(View view) {
Intent smartRecommendedIntent = new Intent(getActivity(), SmartRecommended.class);
startActivity(smartRecommendedIntent);
}
Related
I am using a "Drawer Navigation" project using fragments and so far this method works:
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Navigation.findNavController(view).navigate(R.id.nav_gallery);
}
});
But I want to use the navigation method inside a fragment class calling a function like this:
boolean b;
public void fragmentNavigation() {
if (b) {
Navigation.findNavController(getView()).navigate(R.id.nav_gallery);
}
}
I am a newbie using the navigation architecture and I still don't know if I need to declare some type of action listener for that function or how to make it work.
You can do that, but be careful of :
using getView() is Nullable; so you must make sure that your fragment has already created the view.
You can solve this by a couple of ways
First: Overriding onViewCreated() which has a nonNull view argument
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
fragmentNavigation(view);
}
boolean b;
public void fragmentNavigation(View view) {
if (b) {
Navigation.findNavController(view).navigate(R.id.nav_gallery);
}
}
Second: Create a View field in the fragment class, and set it within onCreateView()
View view;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container,
#Nullable Bundle savedInstanceState) {
view = inflater.inflate(R.layout.main_fragment, container, false);
return view;
}
then always call fragmentNavigation(view); on that view field.
Your fragment is hosted by the NavHostFragment of the Navigation Graph; so that you can avoid potential IllegalStateException
Maybe I am missing something small here, but I cannot get my binding to work. I set it up as follow:
public class Toolbar extends Fragment {
//Interaction handlers
//interface for interaction with Activity
public interface ToolBarInteraction{
public void Search(String screenName);
}
private ToolbarBind modelData;
private ToolBarInteraction mListener;
public static Toolbar newInstance() {
return new Toolbar();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
FragmentToolbarBinding binding = DataBindingUtil.setContentView(getActivity(), R.layout.fragment_toolbar);
modelData = ToolbarBind.newInstance();
modelData.searchedText.set("Hello");
binding.setModelData(modelData);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
checkMListener();
View view = inflater.inflate(R.layout.fragment_toolbar, container, false);
//get button to set onClick event
Button button = (Button)view.findViewById(R.id.btnSearch);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String hello = modelData.searchedText.get();
}
});
return view;
}
public void OnSearchClicked(View view){
mListener.Search(modelData.searchedText.get());
}
private void checkMListener(){
try{
mListener = (ToolBarInteraction) getActivity();
} catch (ClassCastException ex) {
throw new ClassCastException(getActivity().toString()
+ " must implement the ToolBarInteraction Interface");
}
}
}
Here is the code for ToolbarBind:
public class ToolbarBind extends BaseObservable {
private String _searchText;
public final ObservableField<String> searchedText = new ObservableField<String>();
//factory method
public static ToolbarBind newInstance(){ return new ToolbarBind(); }
}
And in my fragment, I set the binding up as follow, all within the layout tag:
<data>
<variable
name="modelData"
type="Common.CommonObjects.ToolbarBind"/>
</data>
And for binding to property:
<EditText
android:layout_width="match_parent"
android:layout_height="match_parent"
android:hint="Search"
android:text="#={modelData.searchedText}"/>
As can be seen, in the onCreate I set the text to "Hello", but even when the view displays on the phone, the EditText is not populated with this text. When I change the value, and click my button, the value I get back in the event is "Hello", not my new text entered while the app is running.
What am I missing?
The problem with your code is that you set the Activity's content view to something in onCreate(...) but you inflate and use something different in onCreateView(...) as your fragment's view, which gets the model data (not the other one you created in onCreate(...)). I don't know exactly what you try to achieve, but I'm gonna guess that you don't want to change the Activity's content view to something from the fragment, so I'm just gonna show you a variation of what could you use, however, you should change it to whatever pleases you.
Remove onCreate(...) completely then use only onCreateView(...) to inflate the fragment_toolbar layout using data binding:
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
checkMListener();
FragmentToolbarBinding binding = DataBindingUtil.inflate(inflater, R.layout.fragment_toolbar, container, false);
// FIXME you're losing data here; watch out: checking whether savedInstanceState == null is not enough because returning from backstack it will be null
modelData = ToolbarBind.newInstance();
// FIXME modify this so it sets the data from savedInstanceState when configuration changes
modelData.searchedText.set("Hello");
binding.setModelData(modelData);
//get button to set onClick event
binding.btnSearch.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
String hello = modelData.searchedText.get();
}
});
return binding.getRoot();
}
Watch out for the FIXME parts. You could move the modelData init to onCreate(...) which would save it from the backstack-return thing, however, configuration change will still call onCreate(...) unless you call setRetainInstance(true) on the fragment (do not).
I have the following Activity:
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new StartFragment())
.commit();
}
Button login = (Button) findViewById(R.id.loginButton);
login.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(MainActivity.this,LoginActivity.class);
startActivity(intent);
}
});
}
I get a NPE when I try to invoke findViewByID for R.id.loginButton, and I'm guessing this is because loginButton is within a separate Fragment, which I have as:
public static class StartFragment extends Fragment {
public StartFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_main, container, false);
}
}
However, I am unsure of how to fix this so that I can find the loginButton ID. I haven't worked with fragments before, so I realize I may be using them/implementing them incorrectly. fragment_main contains a few buttons in a LinearLayout, and activity_main has nothing but a single FrameLayout.
Try to implement your onCreateView(...) in Fragment like
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
View something = rootView.findViewById(R.id.something);
something.setOnClickListener(new View.OnClickListener() { ... });
return rootView;
}
The Button is in the fragment layout (fragment_main.xml) and not in the activity layout (activity_main.xml). onCreate() is too early in the lifecycle to find it in the activity view hierarchy, and a null is returned. Invoking a method on null causes the NPE.
Write code to initialize button from fragment becuase your button is into fragment layout not into activity's layout.
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
Button login = (Button) rootView.findViewById(R.id.loginButton);
login.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(MainActivity.this,
LoginActivity.class);
startActivity(intent);
}
});
return rootView;
}
And remove the login button related code from onCreate of Activity.
findViewById() works with reference to a root view.
Without having a view in the first place will throw a null pointer exception
In any activity you set a view by calling setContentView(someView);.
Thus when you call findViewById() , its with reference to the someView.
Also findViewById() finds the id only if its in that someView. So in you case null pointer exception
For fragments, adapters, activity, .... any view's findViewById() will only find if the id exixts in the view
Alternately if you are inflating a view, then you can also use inflatedView.findViewById() to get a view from that inflatedView
In short make sure you have the id in your layout you are referring to or make findViewById() call in appropriate place(Ex. adapters getView(), activity's onCreate() or onResume() or onPause() , fragments onCreateView(), ....)
Also have an idea about UI & background thread's as you cannot efficiently update UI in bg-threads
i use fragment for my application,they are : Fragment A, Fragment B and Fragment C.
to move from one fragment to another fragment, I use two buttons, the first button is used to move to the next fragment, and the second button is used to return to the previous fragment.
the problems when I move from one fragment to another fragment (such as from A to B and back to A and to B again and to C). all entries in the EditText that is in a fragment is lost and look back empty,it when I go back to the previous fragment, or when I want to go back to the next fragment. I've been using code addToBackStack () when switching to another fragment, indeed EditText that I made not lost when I press the back button on my phone, but it does not affect the buttons (Next And Prev) that I've created. this is Fragment A:
public class AFragment extends Fragment {
EditText text,text2;
public AFragment(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_a, container, false);
ImageView next=(ImageView)rootView.findViewById(R.id.next);
text=(EditText)rootView.findViewById(R.id.text);
text2=(EditText)rootView.findViewById(R.id.text1);
next.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
getFragmentManager().beginTransaction().replace(R.id.frame_container, new BFragment()).addToBackStack(null).commit();
}
});
return rootView;
}
this is Fragment B:
public class BFragment extends Fragment {
EditText cut,cut2;
public BFragment(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View Fragment B = inflater.inflate(R.layout.fragment_c, container, false);
ImageView next=(ImageView)rootView.findViewById(R.id.next);
ImageView prev=(ImageView)rootView.findViewById(R.id.prev);
cut=(EditText)rootView.findViewById(R.id.cut);
cut2=(EditText)rootView.findViewById(R.id.cut2);
next.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
getFragmentManager().beginTransaction().replace(R.id.frame_container, new CFragment()).addToBackStack(null).commit();
}
});
prev.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
getFragmentManager().beginTransaction().replace(R.id.frame_container, new AFragment()).addToBackStack(null).commit();
}
});
return Fragment B;
}
my question is how can i save view in Fragment when user click on next and prev button in my application? is there something missing in my code? i hope someone can help me to solve my problem. thank you very much.
Each fragments have various life cycle methods, you can use onDestroy method and save the required edit text view value calling Activity. For this expose some methods in the calling activity which can be access via fragment. Also else create a singleton class or use Shared Prefences.
I hope this helps.
try to change:
getFragmentManager().beginTransaction().replace(R.id.frame_container, new BFragment()).addToBackStack(null).commit();
to:
getFragmentManager().beginTransaction().add(R.id.frame_container, new BFragment()).addToBackStack(null).commit();
I am trying to add left side slide menu inside my application but i am facing little trouble getting the slide menu to the following child activities of the fragment.
So far i have tried using this sliding menu example and when i got this image now inside the "Find People" fragment class i have static data.
Find People (Parent Activity) on Button Click go to ---> Friends (Child Activity of Find People) on Button Click go to ----> Names (Child Activity of Friends)
I am trying to get the same sliding menu with the Child Activities also that i failed to achieve so far please can any one help me out
public class FindPeopleFragment extends Fragment {
public FindPeopleFragment(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_find_people, container, false);
Button btn = (Button) rootView.findViewById(R.id.butto);
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(getActivity(), Friends.class);
startActivity(intent);
}
});
return rootView;
}
}
Friends (Child Activity)
public class Friends extends Activity {
Button btnNext;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.friends_xml);
btnNext = (Button)findViewById(R.id.btnNexts);
btnNext.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
// Go to Names Child Activity
}
});
}
}
And Similarly Names (Child Activity)
How do i get the same slide menu in both the child activities (Friends & Names). Any idea ??
Plz help me out in this.
Code Snippet will be much helpful.
Thanks
As #Piyush Gupta said you need to call new Fragment instead of calling activities,
In Place of activity you need to use Fragment and move from one Fragment to next used this code
Instead of using Fragment element use Framelayout id of the fragment Xml
Replace ur code with this
public class FindPeopleFragment extends Fragment {
public FindPeopleFragment(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_find_people, container, false);
Button btn = (Button) rootView.findViewById(R.id.butto);
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
FragementDemo fd = new FragementDemo();
android.support.v4.app.FragmentTransaction ft =
getFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, fd); // content_frame is your FrameLayout container
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.addToBackStack(null);
ft.commit();
}
});
return rootView;
}
}
And your next child activity will extend Fragment not Activity like this :
public class Friends extends SherlockFragment{
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragementdemo, container, false);
// use button click code as used in FindPeopleFragment
return rootView;
}
}
Hope it works fine now for you!!