We Keep Coding

How to make SwipeRefreshLayout work when the RecyclerView is empty

I noticed the SwipeRefreshLayout works when my RecyclerView is filled with data but not when the RecyclerView is empty. Is there a way to override this behavior?
My app fetches some data from the server and populates the RecyclerView. So for example, if the user has forgotten to turn on their internet but started my app, I want them to be able to turn it on and swipe up to refresh instead of going back and starting the activity again.
Here's is my activity's xml. I have removed some code to make this less verbose. I had one more button outside of the SwipeRefreshLayout and I have also removed my constraints.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".BreakfastActivity"
android:orientation="vertical">
<android.support.v4.widget.SwipeRefreshLayout
android:id="#+id/b_swipe_refresh_layout"
android:layout_width="match_parent"
android:layout_height="0dp">
<android.support.v7.widget.RecyclerView
android:id="#+id/rv_breakfast"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.v4.widget.SwipeRefreshLayout>
</android.support.constraint.ConstraintLayout>
And this is the .java file:
public class BreakfastActivity extends AppCompatActivity implements SwipeRefreshLayout.OnRefreshListener {
// to display the menu
RecyclerView rv_breakfast;
RecyclerView.Adapter my_adapter;
// the actual menu
ArrayList<Menu> menu;
private SwipeRefreshLayout swipeRefreshLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_breakfast);
rv_breakfast = findViewById(R.id.rv_breakfast);
swipeRefreshLayout = findViewById(R.id.b_swipe_refresh_layout);
swipeRefreshLayout.setRefreshing(true);
swipeRefreshLayout.setOnRefreshListener(this);
rv_breakfast.setLayoutManager(new LinearLayoutManager(this));
new GetMenu(this).execute();
}
#Override
public void onRefresh() {
new GetMenu(this).execute();
}
static class GetMenu extends GetMenuBase {
WeakReference<BreakfastActivity> context;
GetMenu(BreakfastActivity b) {
context = new WeakReference<>(b);
meal_type = "breakfast";
b.swipeRefreshLayout.setRefreshing(true);
}
#Override
protected void onPostExecute(JSONObject parent) {
// process the output of the server side script script
b.swipeRefreshLayout.setRefreshing(false);
}
}
The java file is again devoid of some code not concerning the question. GetMenuBase extends an AsyncTask and implements doInBackground() and makes a call to the server and returns the JSON output.

The problem is that when your RecyclerView is empty then your height will be 0dp because you've set the height to wrap_content and 0dp to your SwipeRefreshLayout.
Change the height of your SwipeRefreshLayout or your RecyclerView to match_parent.

App crashes when trying to call SetSupportActionBar

I have made an app that works fine and uses a default toolbar. However I want to add navigation buttons to this toolbar so I am implementing my own that I can inflate a menu onto it. However when I try to call SetSupportActionBar() the app crashes.
I have tried to set the app to not use the default action bar in both the manifest: <activity android:name=".MainMenu" android:theme="#style/Theme.AppCompat.NoActionBar"/> as well as in the XML file: android:theme="#style/Theme.AppCompat.NoActionBar", as this was the suggested solution for someone else with a similar issue however this has not worked.
The code I am using is as follows;
XML:
<Toolbar
android:id="#+id/my_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
Java:
public class MainMenu extends AppCompatActivity {
Toolbar mToolbar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_menu);
mToolbar = findViewById(R.id.my_toolbar);
setSupportActionBar(mToolbar);
mToolbar.setNavigationIcon(R.drawable.menu_arrow);
mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
}
});
}
}

Change the toolbar's xml to:
<android.support.v7.widget.Toolbar
android:id="#+id/my_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
instead of Toolbar
also look at your imports, if you have this line:
import android.widget.Toolbar;
replace it with:
import android.support.v7.widget.Toolbar;

Fragment Add causing me an error

I am trying to figure out why I am suddenly getting an error when I try to add a fragment.
public class MainActivity extends Activity implements Communicator {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView((int) R.layout.activity_main);
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(R.id.fragA, new FragmentA());
//I get errors on each of the adds
ft.commit();
FragmentTransaction ft2 = getFragmentManager().beginTransaction();
ft2.add(R.id.fragB, new FragmentB());
ft2.commit();
FragmentTransaction ft3 = getFragmentManager().beginTransaction();
ft3.add(R.id.fragC, new FragmentC());
ft3.commit();
}
public void respond(String str) {
//I also get an error on the following line
((FragmentB)getFragmentManager().findFragmentById(R.id.fragB)).changeText(str);
}
}
Just using the import of FragmentTransaction, I haven't made my own class.
This is my fragment A code:
public class FragmentA extends Fragment implements OnClickListener {
Button btn;
Communicator comm;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.fraga, container, false);
}
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
this.btn = (Button) getActivity().findViewById(R.id.buttonA);
this.btn.setOnClickListener(this);
this.comm = (Communicator) getActivity();
}
public void onClick(View v) {
this.comm.respond("Hello from Fragment A");
}
}
xml for the activity, I am not a hundred percent sure if this will fix it but would raising the API of the project make any difference at all?
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
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:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.tannerlangan.week11fragtalk.MainActivity">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="150dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="#ff83ff3e"
android:id="#+id/fragA"></RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="150dp"
android:layout_centerVertical="true"
android:layout_alignParentStart="true"
android:background="#ff71e7ff"
android:id="#+id/fragB"></RelativeLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="150dp"
android:layout_alignParentBottom="true"
android:layout_alignParentStart="true"
android:background="#ff6d9aff"
android:id="#+id/fragC"></RelativeLayout>
</RelativeLayout>

Your fragments probably using android.support.v4.app.Fragment instead of android.app.Fragment. The quick fix is to change the signature of your fragments to something like this:
public class FragmentA extends android.app.Fragment implements OnClickListener
This is very common with programs that mix the components from support libraries and the non-support one

Try using getSupportFragmentManager() instead of getFragmentManager(). getSupportFragmentManager() is for API<14.

In your project check whether you have imported the same Fragment class in both your FragmentA and MainActivity. You might have imported android.support.v4.app.Fragment in your fragment and in MainActivity you may have imported android.app.Fragment.
If you're minSdk is <14 use fragment, fragmentManager etc from the support library(i.e android.support.v4.app.fragment and same for the fragment manager) else just import the standard fragment class(i.e android.app.Fragment).
P.S : It would be really helpfull if you provide your Error in the question as well.

Android Fragment is not displayed

I'm quite new to Android dev and I followed the official Android's "Get started".
The fact is, my fragment is not displayed on the main activity ( it worked well few days ago but I changed some lines, I don't remember which ones ). I think it's a very basic problem as I don't use sophisticated fragments : it's basically one fragment inside an activity.
This is my activity :
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/container1"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.mysecond.MainActivity"
tools:ignore="MergeRootFrame" />
My fragment :
<RelativeLayout 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:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
And the java code for this activity (I have some other activities in the app, based on the same pattern "one fragment inside one activity" and they work well...)
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.container1, new PlaceholderFragment()).commit();
}
}
/**
* A placeholder fragment containing a simple view.
*/
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_main, container,
false);
return rootView;
}
}
}
Any ideas ?
Thank you :)
[edit]
so this is my new onCreate method :
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getSupportFragmentManager().beginTransaction().replace(
R.id.container1, new PlaceholderFragment()).commit();
}
Still not working for this activity (If I add a button in activity_main.xml I'll be able to see it but the I'm not able to see the TextView in the fragment...)
No errors in logcat and yes the activity is launched (I added some Log.e in onCreate and onCreateView and I cas see them)

In your onCreate methode you don't have to check if the savedInstanceState is null but if the the content of the FrameLayout you use is null
Or you simply always replace the fragment with a new one and ommit any checking.

Instead of add, you can use replace.
You can do it like below shown code:
getSupportFragmentManager().beginTransaction().replace(
R.id.container1, new PlaceholderFragment());

For me this work. Implementa a interface FragmentActions with the init() method and use this
private void showFragment(String fragmentTag){
FragmentTransaction trasaction = getSupportFragmentManager().beginTransaction();
FragmentActions fragment = (FragmentActions) getSupportFragmentManager().findFragmentByTag(fragmentTag);
if(fragment==null ){
if(lastFragmentviewed!=null)
trasaction.hide(lastFragmentviewed);
fragment = (FragmentActions) newInstance(fragmentTag);
trasaction.add(R.id.content_frame,(Fragment) fragment,fragmentTag);
}else{
if(lastFragmentviewed!=null && !lastFragmentviewed.equals(fragment))
trasaction.hide(lastFragmentviewed);
if(getSupportFragmentManager().findFragmentByTag(fragmentTag)!=null){
fragment.init();
trasaction.show((Fragment) fragment);
}else
trasaction.add(R.id.content_frame,(Fragment) fragment,fragmentTag);
}
lastFragmentviewed=(Fragment) fragment;
trasaction.commit();
}

Customize the ListView in a Fragment-based Master-Detail Flow?

I found the template that ADT generates for a Master/Detail Flow Activity to be rather obtuse, and I don't like the fact that the ListView is not declared in a layout file which forces me to work with it programatically. For example, instead of just setting android:background on the ListView in a layout file, I'm forced to find the ListView via findViewById in the fragment's onCreateView(...) method, then call setBackground(...). For maintainability and general readability, I'd like to do the same thing via a layout file.
Instead, I'm trying to inflate a custom layout in the onCreateView method of the "master" fragment:
public class InboxFragment extends ListFragment {
public InboxFragment() {}
private ListView listView = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
listView = (ListView) inflater.inflate(R.layout.inbox_fragment_layout,
null);
return listView;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// the following doesn't work
listView.setAdapter(new ArrayAdapter<DummyContent.DummyItem>(getActivity(),
android.R.layout.simple_list_item_activated_1,
android.R.id.text1,
DummyContent.ITEMS));
// nor does this
//setListAdapter(new ArrayAdapter<DummyContent.DummyItem>(getActivity(),
// android.R.layout.simple_list_item_activated_1,
// android.R.id.text1,
// DummyContent.ITEMS));
}
}
However, calling setListAdapter (or even setAdapter) doesn't seem to do anything, even though I've given the ListView an id of android:id="#id/android:list" in R.layout.inbox_fragment_layout:
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#id/android:list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#D3D3D3" />
My "master" activity just calls a fragment layout:
public class InboxActivity extends FragmentActivity {
#Override
protected void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.inbox_phone_layout);
}
}
inbox_phone_layout.xml:
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragmentPhoneInbox"
android:name="com.justin.inbox.InboxFragment"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1" />
Instead, I'm greeted with a blank page and it doesn't look like the ListView is loaded at all. What am I doing wrong, here? Sample project on GitHub.

I fixed your issue by changing inbox_phone_layout.xml to the following:
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragmentPhoneInbox"
android:name="com.justin.inbox.InboxFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />