I have a MainActivity. It's layout contains a fragmentContainer and an actionBar. Then I have 2 different fragments containing various EditTexts.All of them have Ids. I populate the fragmentContainer with the fragments when user clicks a button in actionBar. Everything works perfectly.
Now...the app, is supposed to collect the contents of all EditTexts from both fragments when I push a button (in the menu of the actionBar). But it does not work. It crashes when I try to access the EditTexts directly from the activity. I understand that I should create a public method inside the code of the fragments that will return the values I am interested in. But I seem to be doing something wrong because the method is not accessible from the main (TabActivity)
Here is my code:
public class TabActivity extends Activity {
ActionBar.Tab tab_alocare, tab_merc;
Fragment fragmentTab1 = new aloc_fragment();
Fragment fragmentTab2 = new merc_fragment();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tab); // this layout contains the fragmentContainer
...// here I do some actionBar stuff
}
...
}
An example of one of the fragments is bellow:
public class aloc_fragment extends Fragment {
EditText mEditText;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_aloc, container, false);
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mEditText = (EditText) getView().findViewById(R.id.edaloc);
}
public String getMyText() {
String rez = "";
if (mEditText.getText()!=null) {
rez = mEditText.getText().toString();
}
return rez;
}
}
Now... if inside the Activity code I want to access the edaloc EditText using findViewById, it crashes the app with nullException. So I then tried to access the public method of the fragment so that it would return me the value that I need. But "getMyText" method is not accessible from the TabActivity.
So, this code does not work:
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.save:
Fragment alocfragment = (Fragment) getFragmentManager().findFragmentByTag("aloc");
String s = alocfragment.getMyText(); // this is not compiling at all
I am clearly doing something wrong.
Please advise.
Thank you
There are lots of mistakes in your code, You have neither declared nor initialize the fragments at proper place. Also, you are trying to create another instance of fragment in onOptionsItemSelected which is wrong, you need to use same instance of fragment there to access your functions with values. I hope you know how to add and inflate fragment. See my comments and code changes.
Try with this -
public class TabActivity extends Activity {
ActionBar.Tab tab_alocare, tab_merc;
//Declare fragments here
Fragment fragmentTab1;
Fragment fragmentTab2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tab); // this layout contains the fragmentContainer
//Initialize here
fragmentTab1 = new aloc_fragment();
fragmentTab2 = new merc_fragment();
//inflate/add fragments here to the activity
...// here do your actionBar stuff
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.save:
//Now, use same instance of fragment to access your function
String s = fragmentTab1.getMyText();
}
}
public class aloc_fragment extends Fragment {
EditText mEditText;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_aloc,
container, false);
//hold edittext here in the variable
mEditText = (EditText) view.findViewById(R.id.edaloc);
return view;
}
public String getMyText() {
String rez = "";
if (mEditText.getText()!=null) {
rez = mEditText.getText().toString();
}
return rez;
}
}
Also, must to go through Fragment tutorial on Android Developer Fragment Link Link 2, Using Fragments
Related
I have a fragment with multiple toggle buttons. On click of a particular button in my Activity, I'd like to upload the status of all these toggle buttons to the server. I see there is one way of doing it as explained in the below link, where we create a listener interface and on every click of each toggle button, we update some tag/integer in the activity corresponding to each toggle button.
https://developer.android.com/training/basics/fragments/communicating.html
But I would like to know if there is any way to know the checked/unchecked status of all toggle buttons in the fragment from the activity without implementing the interface methods for each time a toggle button is clicked. Hope I'm clear.
Here's a working example of how to achieve that. The activity:
public class MainActivity extends AppCompatActivity {
ToggleFragment toggleFragment;
Button updateStatusButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
updateStatusButton = (Button) findViewById(R.id.updateStatusButton);
toggleFragment = ToggleFragment.newInstance();
getSupportFragmentManager().beginTransaction()
.replace(R.id.main_frame, toggleFragment, "ToggleFragment")
.commit();
updateStatusButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
boolean buttonsChecked = toggleFragment.areToggleButtonsChecked();
Toast.makeText(MainActivity.this, String.format("Toggle buttons checked: %s", buttonsChecked), Toast.LENGTH_LONG).show();
}
});
}
}
And the Fragment:
public class ToggleFragment extends Fragment {
ToggleButton toggleButton1;
ToggleButton toggleButton2;
ToggleButton toggleButton3;
public static ToggleFragment newInstance() {
Bundle args = new Bundle();
ToggleFragment fragment = new ToggleFragment();
fragment.setArguments(args);
return fragment;
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.toggle_fragment, container, false);
toggleButton1 = (ToggleButton) view.findViewById(R.id.toggleButton1);
toggleButton2 = (ToggleButton) view.findViewById(R.id.toggleButton2);
toggleButton3 = (ToggleButton) view.findViewById(R.id.toggleButton3);
return view;
}
public boolean areToggleButtonsChecked() {
return toggleButton1.isChecked()
&& toggleButton2.isChecked()
&& toggleButton3.isChecked();
}
}
Honestly, the best way that you could accomplish this is with a ViewModel from the Android Architecture Components library. The ViewModel can have an ObservableField or LiveData value that each of the Fragments can observe, and always have the correct information. This would also make it easier to be lifecycle-aware.
I have 4 fragments inside my viewpager and I want to get the edit text value from another fragment. E.g :
I'm in the third fragment and I want to get the value of the Edit text inside the first fragment.
How can I do to do that ?
Interface is your best option.
As the fragment in viewpager is recreated every time. you cannot store values inside fragment and get it properly.
Create variable to hold editext value in ViewPager Hosting Activity.
String editext_fragment1;
Use Interface to write and get values from this variable from any fragments .
Try getActivity().findViewById(), if you are not re-using the same id anywhere in other fragments. Check if it is null or not, then use it.
Hope it will help :)
In your MainActivity create a function and a global variable (setter and getter)
private EditText mEditText;
public EditText getEditText(){
return mEditText;
}
public void setEditText(EditText et){
this.mEditText = et;
}
In your FirstFragment
((MainActivity) getActivity()).setEditText(YOUR_EDITTEXT);
In your ThirdFragment where you need to get the EditText value
if( ((MainActivity) getActivity())getEditText() != null ){
((MainActivity) getActivity())getEditText().getText();
}
To do that you should pass your value through the constructor of your fragment.
For exemple you have your first fragment with a button that will call the secondFragment:
public class myFirstFragment extends Fragment implements View.OnClickListener {
private Button myButton;
private EditText myEdit;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.myFirstFragment_layout, container, false);
myButton = (Button) rootView.findViewById(R.id.buttonId);
myEdit = (EditText) rootView.findViewById(R.id.editTextId);
myButton.setOnClickListener(this);
return rootView;
}
#Override
public void onClick(View v) {
Fragment fragment;
switch (v.getId()) {
case R.id.buttonId:
fragment = new mySecondFragment(myEdit.getText().toString().trim());
break;
}
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.contenedor_frag, fragment).commit();
}
}
And in your second Class you should have this:
public class mySecondFragment extends Fragment {
private String myEditFirstFragment;
public mySecondFragment (String _editFirstFrag) {
this.myEditFirstFragment = _editFirstFrag;
}
}
Hope that helps,
I have four fragments in an Activity C. they are behaving as tabs. I have to go from a fragment to a new Activity X. Now i want to come back to fragment from Activity X to fragment.
here is my main activity
'public class MainInterface extends ActionBarActivity {
ViewPager pager;
PagerTabStrip tab_strp;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_interface);
MainPagerAdapter mapager = new MainPagerAdapter(getSupportFragmentManager());
pager = (ViewPager) findViewById(R.id.pager);
pager.setAdapter(mapager);
tab_strp = (PagerTabStrip) findViewById(R.id.tab_strip);
//tab_strp.setTextColor(Color.WHITE);
//tab_strp.setTextSize(14,14);
//tab_strp.setTabIndicatorColor(Color.WHITE);
getSupportActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#2196f3")));
getSupportActionBar().setTitle("Instructor");
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
//getSupportActionBar().setHomeButtonEnabled(true);
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// app icon in action bar clicked; goto parent activity.
this.finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}
'
here is activity
'public class Discussions extends Fragment implements View.OnClickListener {
ImageButton post;
TextView dTitle;
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View view =inflater.inflate(R.layout.discussions,container,false);
post=(ImageButton)view.findViewById(R.id.ibDisc);
post.setOnClickListener(this);
dTitle=(TextView)view.findViewById(R.id.tvDiscTitle);
return view;
}
#Override
public void onClick(View view) {
Intent in=new Intent(getActivity(),PostDiscussion.class);
startActivity(in);
}
}'
Save the name of your fragment in sharedPreferences before navigating to new activity and onBackpressed of that new activity or when you want to come back to same fragment get the name from SharedPreferences and add that particular fragment to the earlier activity
On my screen I have 2 containers - left for 3 fragments in view pager, right for single fragment. From this on the right I increment some temp variable and through inteface I pass this variable to fragments. I switch fragments in view pager and everything seems to act all right. But, there are two problems.
First is that when I start my app and try to actualize temp variable in third fragment in view pager there is NPE. And of course it should be, because at this point third fragment is not initialized (view pager only initialize actual fragment and the ones on his sides, to be able to slide between fragments). How can I initialize third fragment at the begining? I thought I can store data temporarily in second fragment and when second is initialized I can pass the data to third, but it seems not good solution.
Second question is when I initialize all fragments by sliding on it and I come back to first fragment view of third is gone (but it's initialized). When I actualize temp variable and slide to third fragment I can see this variable but after +- one second. Can someone explain me why? Without this knowledge I can't solve this problem :/
Here you have some code of mine:
public class ThirdFragment extends Fragment {
View thisView;
TextView tempTextView;
String iterator;
public AchievFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
iterator = "Start";
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
thisView = inflater.inflate(R.layout.fragment_third, container, false);
tempTextView= (TextView) thisView.findViewById(R.id.tempTextView);
tempTextView.setText(iterator);
return thisView;
}
public void getVariable(String text) {
iterator = text;
tempTextView.setText(iterator);
}
So it's third fragment class. At the beginning I initialize iterator (it's this temp variable) as a global variable to avoid npe after initializing fragments. And in onCreateView i set the view of TextView to value of this variable. Should work fine, but this +-1 sec offset makes me sad.
I think this sample of code should be enough, the rest is standard I suppose, but if anyone will be really interested I'll past the rest.
I really hope you will understand what I just wrote.
Here is the main (hosting) activity code:
public class MainActivity extends AppCompatActivity implements OnFragmentInteractionListener {
ViewPager mViewPager;
FragmentPageAdapter ft;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewPager = (ViewPager) findViewById(R.id.pager_container);
ft = new FragmentPageAdapter(getSupportFragmentManager());
mViewPager.setAdapter(ft);
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
RightFragment gameFragment = new RightFragment();
ft.replace(R.id.rightFragment_container, rightFragment,"RightFragment");
ft.commit();
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
return super.onOptionsItemSelected(item);
}
#Override
public void OnUpdateFirst(String text) {
FirstFragment firstFragment = (FirstFragment) ft.instantiateItem(mViewPager,0);
firstFragment.getVariable(text);
}
#Override
public void OnUpdateSecond(String text) {
SecondFragment secondFragment = (SecondFragment) ft.instantiateItem(mViewPager,1);
secondFragment.getVariable(text);
}
#Override
public void OnUpdateThird(String text) {
ThirdFragment thirdFragment = (ThirdFragment) ft.instantiateItem(mViewPager,2);
thirdFragment.getVariable(text);
}
}
Fragment Page Adapter code:
public class FragmentPageAdapter extends FragmentPagerAdapter {
public FragmentPageAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int arg0) {
switch (arg0)
{
case 0:
return new FirstFragment();
case 1:
return new SecondFragment();
case 2:
return new ThirdFragment();
default:
break;
}
return null;
}
#Override
public int getCount() {
return 3;
}
Expection when I try to actualize variable on third fragment before I initialize it (in example right after I start app)
06-14 16:47:25.621 27246-27246/com.package.app E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.NullPointerException
at com.package.app.ThirdFragment.getVariable(ThirdFragment.java:37)
at com.package.app.MainActivity.OnUpdateThird(MainActivity.java:59)
at com.package.app.RightFragment$3.onClick(RightFragment.java:57)
at android.view.View.performClick(View.java:4101)
at android.view.View$PerformClick.run(View.java:17082)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4940)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:798)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:565)
at dalvik.system.NativeStart.main(Native Method)
As to your first question you can call setOffscreenPageLimit(2) method on your ViewPager right after initializing it. By default it is set to 1 that means that adapter creates one page which is on the screen right now and one that is next.
Any time the main Activity is started or restarted (i.e. by pressing the home button on my action bar), all of the buttons (which reside in a fragment in this main activity) work correctly. However, if I press one of the buttons, then press the back button, the home fragment and its buttons reappears but none of the button callbacks work. The button images continue to change appearance when pressed, as always.
The callbacks are assigned in the onCreateView method of the home fragment, as follows:
public class HomeFragment extends SherlockFragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Button button = (Button) v.findViewById(R.id.button);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Log.d(TAG, "Button!");
mActivity.getSupportFragmentManager().beginTransaction()
.replace(R.id.contFragMain, new SomeFragment())
.addToBackStack(null)
.commit();
}
});
}
Here is the superclass of Fragments I launch with the buttons:
public abstract class RouteListFragment extends SherlockFragment {
private static final String TAG = RouteListFragment.class.getName();
private Activity mActivity; // parent activity
RouteListAdapter mAdapter;
ListView mListViewRouteList;
public RouteListFragment() {
super();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mActivity = getActivity();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
Bundle bndl = getArguments(); // data passed should contain search term
View v = inflater.inflate(R.layout.fragment_route_list, container, false);
mListViewRouteList = (ListView) v.findViewById(R.id.listViewRouteList);
addRoutesToList(); //Populates the list with data via an async DB call
return v;
}
You shouldn't be stashing the Activity reference; the Activity is probably getting recreated at some point (depends on how your flow is), but you should either reassign the reference in onAttach (Activity activity), or just call getActivity() to get the currently Activity you're attached to.
So mActivity.getSupportFragmentManager()...
should instead be
getActivity().getSupportFragmentManager()...
EDIT: Wait, maybe that's not right. What is v in onCreateView()? You're not creating any UI in this Fragment? You should be using onViewCreated() to get a reference to the views in the created hierarchy.