While debugging another issue, I realized that the onCreateView method of one of my activities was being called twice. I'm new to programming and I don't fully understand how android calls these methods when the activity loads, but it doesn't seem right to me that it would be called twice. Eliminating most of my code, I still see my System.out message twice.
public class AddCourse extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add_course);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new AddCourseFragment()).commit();
}
}
public static class AddCourseFragment extends Fragment {
View rootView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_add_course,
container, false);
System.out.println("I see this TWICE!!!!");
return rootView;
}
}
}
This is almost exactly like my main activity implementation, but that one doesn't go through onCreateView twice. Thoughts?
My activity_add_course xml was requested...
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/container"
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment android:name="com.NsouthProductions.gradetrackerpro.AddCourse$AddCourseFragment"
android:id="#+id/AddCourseFrag"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
Looks like you're adding the fragment twice. If you declare it in the xml then you don't need to add it programmatically as well.
You can remove this from your Activity's onCreate():
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new AddCourseFragment()).commit();
}
Related
I wanna open fragment from my activity. The problem is that the fragment never appears.
This is the part of my activity:
btn_opciones.setOnValueChangedListener(new ToggleButton.OnValueChangedListener() {
#Override
public void onValueChanged(int position) {
if(position == 1){
OrdenarComplejosFragment ordenarComplejosFragment = new OrdenarComplejosFragment();
FragmentManager manager = getSupportFragmentManager();
FragmentTransaction ft = manager.beginTransaction();
ft.setCustomAnimations(R.anim.fade_in, R.anim.fade_out);
ft.add(ordenarComplejosFragment, null);
ft.commit();
}
}
});
And this is my fragment that I wanna open and show:
public class OrdenarComplejosFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_ordenar_complejos, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//do your stuff for your fragment here
}
}
The xml of the fragment above:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="HOLAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
android:id="#+id/textView35"
android:layout_gravity="center_horizontal" />
</LinearLayout>
I don't know why the fragment never show. The button works fine.
Try using a different "add" method. Using the one which takes in a view id indicates where the fragment should show up within the existing Activity's layout.
ft.add(R.id.fragment_frame, ordenarComplejosFragment);
Fragments are always housed within an Activity. If your activity doesn't provide a container/location for the fragment to show up, you'll need to re-think the layout or consider opening this new view with a separate Activity.
So, I'm following the steps in the Android API to add login to my app. My app is already fairly developed, and of course I'm no to android, so I'm having issues at this point.
the step reads:
Then set up the button in your UI by adding it to a fragment and update your activity to use your fragment.
I've searched for how to add a fragment and anything about that, watched youtube videos, but can't find out exactly what this means. Can anyone dumb this down for me?
https://developers.facebook.com/docs/facebook-login/android
First, you need a hosting activity, extending AppCompatActivity that has a FrameLayout in its related layout file. Then you inflate the layout in the onCreate method and add the needed Fragment:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (findViewById(R.id.fragment_placeholder) != null) {
if (savedInstanceState != null) {
return;
}
// we are extending AppCompatActivity, so we need supportFragmentManager
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_placeholder, new ContentFragment()).commit();
}
}
}
The according layout file activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_placeholder"
android:layout_width="match_parent"
android:layout_height="match_parent">
</FrameLayout>`
Now you need to define ContentFragment:
public class RecordFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
return inflater.inflate(R.layout.fragment_content, container, false);
}
}
The last step is the layout file for our fragment, fragment_content, containing a Button:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</RelativeLayout>
For more information why we use AppCompatActivity, read this answer.
This question already has answers here:
NullPointerException accessing views in onCreate()
(13 answers)
Closed 8 years ago.
I have a problem that seems to be quite common on the internet : I have created an activity with just a fragment. This is the generated code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_customer);
if (savedInstanceState == null) {
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
ListView lv = (ListView) findViewById(android.R.id.list);
}
}
After or inside the condition, I can't get any object with findViewById: it is always null. Here is the rest of the generated code :
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_customer,
container, false);
return rootView;
}
activity_customer.xml:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.axacs.marc.CustomerActivity"
tools:ignore="MergeRootFrame" />
the listview is actually in fragment_customer.xml:
<ListView
android:id="#android:id/list"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/new_folder_button"
android:text="" />
Does anyone know what is missing ?
use following after moving this line to onCreateView() if you want to use your listview in your fragment
ListView lv = (ListView)rootview.findViewById(android.R.id.list);
I'm trying to setup a FragmentStatePagerAdapter to create a scrollable tab interface on one of my fragments similar to this example. In my activity's onCreate:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.base);
setVersionString();
setupActionBar();
setupNavigationDrawer();
setupFragments();
}
I set the content view to the following layout (R.layout.base):
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".BaseActivity" >
<!-- The main content view -->
<FrameLayout
android:id="#+id/main_frame"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<!-- The navigation drawer -->
<ListView
android:id="#+id/nav_drawer"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:choiceMode="singleChoice"
android:divider="#android:color/transparent"
android:dividerHeight="0dp"
android:background="#FFF" />
</android.support.v4.widget.DrawerLayout>
I then call the following function:
private void setupFragments() {
// Check that the activity is using the correct layout
if (findViewById(R.id.main_frame) != null) {
// Initialize the first fragment
MainFragment firstFrag = new MainFragment();
// Pass any extras from an intent to the Fragment
firstFrag.setArguments(getIntent().getExtras());
// Add the first Fragment to the screen
getSupportFragmentManager().beginTransaction()
.add(R.id.main_frame, firstFrag).commit();
tabsAdapter = firstFrag.getAdapter();
Log.d("Base.LOG", "tabsAdapter = " + tabsAdapter);
tabsAdapter.addTab(DummyFragment.class, null);
}
}
In an attempt to set a FragmentStatePagerAdapter as the adapter for the view in the fragment's layout (R.layout.main):
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_page"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainFragment" >
<android.support.v4.view.PagerTitleStrip
android:id="#+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:background="#33b5e5"
android:textColor="#fff"
android:paddingTop="4dp"
android:paddingBottom="4dp" />
</android.support.v4.view.ViewPager>
And my fragment's code looks lie this:
private View mView;
private TabbedPagerAdapter mTabPageAdapter;
private ViewPager mTabPager;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Log.d("Main.LOG", "onCreate called");
mView = inflater.inflate(R.layout.main, container, false);
Log.d("Main.LOG", "Layout inflated");
setupTabs();
Log.d("Main.LOG", "Tabs setup");
return mView;
}
#Override
public void onResume() {
super.onResume();
Log.d("Main.LOG", "onResume called");
}
/** Set up the ViewPager and Adapter to handle the primary tabs */
private void setupTabs() {
// Initialize the adapter
mTabPageAdapter = new TabbedPagerAdapter(getActivity(),
getActivity().getSupportFragmentManager());
// Initialize the view pager
mTabPager = (ViewPager) mView.findViewById(R.id.main_page);
Log.d("Main.LOG", "mTabPager = " + mTabPager);
Log.d("Main.LOG", "mTabPageAdapter = " + mTabPageAdapter);
mTabPager.setAdapter(mTabPageAdapter);
}
/* Accessor for TabbedPagerAdapter */
public TabbedPagerAdapter getAdapter() {
return mTabPageAdapter;
}
The app force closes when I try to add a tab with a NullPointerException. The debug messages in the log show that:
D/Base.LOG(27173): tabsAdapter = null
is displayed before any of the fragment's debug messages. How can I ensure that the layout is inflated before trying to access any of it's Views or subclasses?
As per my comment
public class MainFragment extends Fragment
{
private MainInterface mInterface = null;
//make sure to set the above somehow
public interface MainInterface{
public void onFragmentReady(.....);
}
... //Do regular stuff here
public void onResume()
{
//Do what you need to do in onResume
if(mInterface != null)
{
mInteface.onFragmentReady();
}
}
}
This should allow you to know when the fragment is ready and you can do your getTabAdapter calls then.
Are you calling setContentView(...) inside the onCreate(...) method of your Activity before calling setupFragments(...)?
If yes: Does the layout you are assigning to the Activity contain the ViewPager?
My recommendation: Since you are obviously using a ViewPager inside a Fragment, do the initialization of the ViewPager inside the Fragments onCreateView(...) method.
Example:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
// ASSUMING your layout.main contains the ViewPager
View v = inflater.inflate(R.layout.main, container, false);
ViewPager pager = (ViewPager) v.findViewById(R.id.pager);
// and so on ...
return v;
}
I guess everybody knows the project that is created when you choose "master detail flow" when creating your project in eclipse.
Theres layouts for the left side, for the right side and a two_pane layout with a fragment and a Framelayout as a fragment container. This works fine.
Now I have a 'main' activity A with a viewpager, fragments etc., and i call the activity from a fragment with the Callback. From that activity A I start a new activity B. That activity B is set up exactly like that example activity from eclipse that I just talked about.
Now I have the problem that the app crashes with
ERROR/AndroidRuntime(8105): Caused by: java.lang.IllegalArgumentException: Binary XML file line #57: Duplicate id 0x7f080024, tag null, or parent id 0x0 with another fragment for FragmentNumber3
When I replace the fragment in the two_pane layout with another framelayout, it doesn't crash.
This problem is typical for nested fragments, but I don't have nested fragments here, right? I have an activity B that, at that point, doesn't have anything to do with my activity A.
What's the problem here?
Edit: This is my Activity B:
public class SucheActivity extends FragmentActivity implements
SearchboxFragment.SearchboxListener {
private boolean mTwoPane;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.searchbox);
getActionBar().setDisplayHomeAsUpEnabled(true);
if (findViewById(R.id.searchresult_container) != null) {
mTwoPane = true;
}
}
}
And thats the two_pane layout for the activity, the searchbox should be left, the searchresults right:
<LinearLayout 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"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp"
android:baselineAligned="false"
android:divider="?android:attr/dividerHorizontal"
android:orientation="horizontal"
android:showDividers="middle" >
<fragment
android:id="#+id/searchbox_fragment"
android:name="com.example.layouttest.SearchboxFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1"/>
<FrameLayout
android:id="#+id/searchresult_container"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="3" />
</LinearLayout>
Heres the SearchboxFragment class:
public class SearchboxFragment extends Fragment {
SearchboxListener mCallback;
View v;
public interface SearchboxListener {
public void onSearchStarted();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
v = inflater.inflate(R.layout.searchbox, container, false);
return v;
}
}
The searchresultfragment:
public class SearchResultFragment extends Fragment {
public SearchResultFragment() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.searchresult, container, false);
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
}
}
And the refs.xml in res/values-large:
<resources>
<item name="searchbox" type="layout">#layout/haussuche_twopane</item>
</resources>
Okay, so this is what I found out:
I cant set the layout of my Activity to searchbox.xml (and have it alias'd in refs.xml with two_pane.xml) AND set the Layout of SearchboxFragment to searchbox.xml.
I thought that searchbox.xml was never shown by the Activity in two-pane-mode, I could safely set it elsewhere, but that's wrong.
What I did was copy that layout and use a searchbox_onepane.xml and searchbox_twopane.xml.