Just created a new project in the newest ADT release in Eclipse and found that it will setup up certain environments for you to get things started. I choose Tabs + Swipe.
It has this code I have question on:
public static class DummyFragment extends Fragment {
public DummyFragment () {
}
public static final String ARG_SECTION_NUMBER = "section_number";
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
TextView textView = new TextView(getActivity());
textView.setGravity(Gravity.CENTER);
Bundle args = getArguments();
textView.setText(Integer.toString(args.getInt(ARG_SECTION_NUMBER)));
return textView;
}
}
Both tabs refer to this same fragment. All it does is switch the content on the TextView that has the tab position number on it (1,2, or 3).
The more advanced question first: I want two different Fragments that the tab switches to. In the example code, it points to the same fragment. Where does this change take place? and can I see brief code example?
Easier question: I have two pre-defined XML layouts I'd like to set each tab (or Fragment) with. Do I do this in the actual Fragment? And if so, where? setContentView does't seem to be working in the onCreateView method?
Not really sure what this question is asking exactly, but if I understand correctly the TabHost (or whatever you are using to manage the Fragment tabs) is instantiating multiple instances of the DummyFragment and then attaching each to the screen when a tab is clicked. This is all done behind the scenes... all you need to worry about is implementing the Fragment and telling the TabHost when it should be instantiated/displayed.
Fragments don't have a setContentView method. You should inflate your Fragment's layout from xml in onCreateView. For instance with,
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_layout, container, false);
}
Related
I am trying to write a test app which contains an activity. There are two fragments inside this activity, which are defined as LeftFragment and RightFragment. I used getFragmentManager().findFragmentById() to get connection from each other fragments. By using that methode I am able to get an LeftFragment object from RightFragment, but not RightFragment object from LeftFragment. It just works only oneway. I am doing this, because I want to call some operations from other fragment, that return some values. I was thinking about using EventBus but I failed too. How can I achive that?
Here is my LeftFragment
public class LeftFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
RightFragment rightFragment = (RightFragment) getFragmentManager().findFragmentById(R.id.rightFragment);
if (rightFragment != null){
makeToast(rightFragment.getMessageFromRight());
}else {
makeToast("does not found rightFragment");
}
return inflater.inflate(R.layout.fragment_left, container, false);
}
public String getMessageFromLeft(){
return "Hi! Im left";
}
private void makeToast(String text){
Toast.makeText(getContext(),text,Toast.LENGTH_SHORT).show();
}
}
And here is my RightFragment
public class RightFragment extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
LeftFragment leftFragment = (LeftFragment) getFragmentManager().findFragmentById(R.id.leftFragment);
if (leftFragment != null){
makeToast(leftFragment.getMessageFromLeft());
}else {
makeToast("does not found leftFragment");
}
return inflater.inflate(R.layout.fragment_right, container, false);
}
public String getMessageFromRight(){
return "Hi! Im right!";
}
private void makeToast(String text){
Toast.makeText(getContext(),text,Toast.LENGTH_SHORT).show();
}
}
There are many ways to communicate between 2 fragments . If 2 fragments loaded at the same time. I usaually use one of 2 ways below to do it.
You can use this link using obserable pattern to communication 2 fragments.
you can use EventBus lib for communication, it 's very simple
Your issue:
By using that methode I am able to get an LeftFragment object from
RightFragment, but not RightFragment object from LeftFragment
I think your problem is LeftFragment is intitialized previous, so you can find it from RightFragment. Your solution is ok, using EventBus. YOu need to review your codes to find the issue. You can test by creating other methods, after 2 fragment was initialized.
For ex: click button in LeftFragment, toast a message in RightFragment.
Probably what is happening is that the Left Fragment is getting the OnCreateView() call first, at which point the Right Fragment has not been inflated yet (therefore it can't be "found" by findFragmentbyId()).
I would suggest moving the code that gets the references to the other fragments into onStart(), and only inflate the fragments in onCreateView().
Right now I'm making an app that requires me to have about 20 or more different pages/layouts, one loaded at a time, but little/no intercommunication between them. They would be very static. Right now I had the idea to have one activity, one fragment that would inflate a different layout in the onCreateView, and the fragment would be reloaded everytime the user selected another page. However I just realized that wouldn't work at all because I can't put the return statement of onCreateView in an if statement, and no workaround work.
So now I don't know the most efficient way to do this. There's no way having 20+ layouts and 20+ classes, one for each page is ideal. It seems very redundant.
You can use the Fragment's bundle to communicate to it which layout to use.
In the Fragment class, create a static method to create the Fragment instance and set it's bundle, for example:
public static MyFragment newInstance(int layoutId) {
MyFragment f = new MyFragment();
Bundle args = new Bundle();
args.putInt("layoutId", layoutId); // e.g. layoutId = R.layout.layout_fragment_01
f.setArguments(args);
return f;
}
and then in the fragment's onCreateView, get the layout id from the bundle:
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(getArguments().getInt("layoutId", 0), container, false);
}
then, in your Activity, you'd do something like the following:
MyFragment fragment = MyFragment.newInstance(R.layout.fragment_layout_01);
getFragmentManager().beginTransaction().add(android.R.id.content, fragment).commit();
I have 3 tabs, and I'm trying to show a different activity and layout each tab.
I am using the tabs as my app navigation, so when a has changed, the whole layout and activity need to be changed.
Actually only the layout is changing.
Since the MainActivity.java + layout has the PageAdapter in it (the PageAdapter is loading the tab's content),
I have moved my first page activity from the MainActivity.java to a new java activity called showUpdates.java. Now I'm trying to access this activity as my Tab #1 content.
If you still didn't understand what I'm asking for, The following will make it clear:
My 3 tabs are:
Java: TabFragment1.java, XML: activity_show_updates.xml
Java: TabFragment2.java, XML: tab_fragment_2.xml
Java: TabFragment3.java, XML: tab_fragment_3.xml
The TabFragment1.java:
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
/**
* Was trying:
* Intent intent = new Intent(...)
* startActivity(intent);
*/
return inflater.inflate(R.layout.activity_show_updates, container, false);
}
As you can see, it's moving to a new layout, activity_show_updates.xml.
What I'm trying to do is - using my showUpdates.java as the Activity of the tab_fragment_1.
I've been trying to use Intent but my app crashed when I created it at TabFragement1.java.
Anyone knows how I can make showUpdates.java as the activity of this layout?
You cannot nest activities. There are fragments for that. Just create a different fragment for each tab and use an Activity to hold all of them. If you need it, you can also create child fragments (although the support is not so good and you might have some problems, but nothing really hard to handle).
If you have viewpager working, you can do the following:
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return NUM_ITEMS;
}
#Override
public Fragment getItem(int position) {
if(position == 0){
//return first fragment
}
else if(position == 1){
//return second fragment
}
...
}
and you can do your onCreate logic in onCreateView:
public override View OnCreateView (LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View yourFragment = inflater.inflate (Resource.Layout.fragment_name, container, false);
... //do stuff
return yourFragment;
}
All you need to do is define which fragments to output in your adapter
I'm creating an application with a CustomPagerAdapter that can be controlled by ActionBar tabs or horizontal swipe. When you select a tab, a fragment corresponding to that tab is displayed on the screen. When the app is created and when any tab is selected, the adjacent tabs, fragments are loaded into memory. I do not want this to happen. I would like it so that when a tab is selected only that selected tab's fragment is loaded into memory. Is there a way to do this?
Edit: The code I'm currently having trouble with is as follows:
public class fragA extende Fragment
{
private VideoView videoViewA;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View rootView = inflater.inflate(R.layout.fragment_A, container, false);
videoViewA = (VideoView) rootView.findViewById(R.id.videoViewA);
return rootView;
}
#Override
public void setUserVisibleHint(final boolean isVisibleToUser)
{
super.setUserVisibleHint(isVisibleToUser)
if (isVisibleToUser)
{
videoViewA.setVideoURI(LINK);
videoViewA.start();
}
else
{
videoViewA.stopPlayback();
}
}
}
The error I'm receiving is at the videoViewA.setVideoURI(LINK); line. Mind you, the link is actually there, but for privacy reasons I cannot post it.
Edit 2: It's ajava.lang.NullPointerException.
Edit 3: Sorry, but I'm doing this all the hard way. The code now reflects what I have actually written.
Try loading your videos within setUserVisbleHint(), which gets fired by the FragmentPageAdapter upon showing the fragment.
http://developer.android.com/reference/android/support/v4/app/Fragment.html#setUserVisibleHint(boolean)
If that doesn't work for you, you can also try to do check onHiddenChanged(boolean hidden).
http://developer.android.com/reference/android/app/Fragment.html#onHiddenChanged(boolean)
I made a program that uses FragmentTabs for implementing ActionBar Tabs.
I was wondering how it is possible to add a widget to a inflated Fragments in Tabs. It's more complicated than normal because the fragment is returning only an onCreateView to the TabListener, so how would I add in functioning widgets? I don't need specific code, just the logic please!
Here is a sample Fragment being inflated when a Tab is clicked (inside of which I need widgets):
public class IdFragment extends Fragment{
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
// Inflate the layout for this fragment
return inflater.inflate(R.layout.id_layout, container, false);
}
}