Android - Using AppCompat/ActionBar for older devices(java.lang.NullPointerException) - android

I have an application which currently works on Android versions 4.x and more.
I am trying to change it so it can be usable by older devices such as 2.x and more.
Everything is working fine except the action bar. I am getting a null pointer exception every time I am trying to getSupportActionBar. This is am issue that have been discussed a lot in forums but I still cannot solve it.
The application uses the appCompat library but it does not seem to work on older devices.
styles.xml file
<style name="AppBaseTheme" parent="Theme.MyApp">
<item name="android:spinnerItemStyle">#style/SpinnerItem</item>
<item name="android:spinnerDropDownItemStyle">#style/SpinnerItem.DropDownItem</item>
<item name="android:windowNoTitle">true</item>
</style>
MyApp.xml file
<style name="Theme.MyApp" parent="#style/Theme.AppCompat">
<item name="actionBarItemBackground">#drawable/selectable_background</item>
<item name="popupMenuStyle">#style/PopupMenu.MyApp</item>
<item name="dropDownListViewStyle">#style/DropDownListView.MyApp</item>
<item name="actionBarTabStyle">#style/ActionBarTabStyle.MyApp</item>
<item name="actionDropDownStyle">#style/DropDownNav.MyApp</item>
<item name="actionBarStyle">#style/ActionBar.Transparent.MyApp</item>
<item name="actionModeBackground">#drawable/cab_background_top</item>
<item name="actionModeSplitBackground">#drawable/cab_background_bottom</item>
<item name="actionModeCloseButtonStyle">#style/ActionButton.CloseMode.MyApp</item>
Activity trying to get the actionbar
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_auction_list);
if (android.os.Build.VERSION.SDK_INT >=11)
{
getActionBar().setIcon(R.drawable.gem);
getActionBar().setDisplayHomeAsUpEnabled(false);
this.getActionBar().setDisplayShowCustomEnabled(true);
this.getActionBar().setDisplayShowTitleEnabled(false);
LayoutInflater inflator = (LayoutInflater)this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflator.inflate(R.layout.actionbar_title, null);
((CFTextView)v.findViewById(R.id.actionbarTitle)).setText(this.getTitle());
//assign the view to the actionbar
this.getActionBar().setCustomView(v);
}
else
{
//This calls a private class inside the same class to get a supported action bar
notActionBar nab = new notActionBar();
nab.getNotActionBar(); //THIS IS THE ERROR LINE
}
Private class that gets the supported action bar. I have used a private class instead of directly getting the actionbar because i could not extend the ActionBarActivity because the activity all ready extends fragments.
private class notActionBar extends ActionBarActivity {
public void getNotActionBar(){
ActionBar actionBar = getSupportActionBar(); //NULL POINTER EXCEPTION
actionBar.setIcon(R.drawable.gem);
actionBar.setDisplayHomeAsUpEnabled(false);
actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
actionBar.setDisplayShowCustomEnabled(true);
this.getSupportActionBar().setDisplayShowCustomEnabled(true);
this.getSupportActionBar().setDisplayShowTitleEnabled(false);
LayoutInflater inflator = (LayoutInflater)this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflator.inflate(R.layout.actionbar_title, null);
((CFTextView)v.findViewById(R.id.actionbarTitle)).setText(this.getTitle());
//assign the view to the actionbar
this.getSupportActionBar().setCustomView(v);
}
public void setTitleActionBar(String a){
getSupportActionBar().setTitle(a);
}
}

you should not try to instantiate Activities like this in Android:
notActionBar nab = new notActionBar();
the way to start Activities in Android is with startActivity(Intent intent) or startActivityForResult method.
But anyhow, The solution for your Problem should be extending ActionBarActivity instead FragmentActivity in your main Activity.
You can do this also if you use Fragments! Because ActionBarActivity extends FragmentActivity.
see related answer here

You should also consider using only getSupportActionBar() or getActionBar() either one of them. Since you wanna target earlier version, use only getSupportActionBar() and remove all the refernces to getActionBar() from your code.
A complete guide to Action Bar is here.

Related

Unable to get the ActionBar ID using AppCompat Activity

Unable to get the id with the below code when updated to AppCompatActivity.
int abContainerViewID = context.getResources().getIdentifier("action_bar_container", "id", "android");
return (FrameLayout) ((AppCompatActivity) context).findViewById(abContainerViewID);
The above method is returning Null now.
This is my App Theme
<style name="AppBaseTheme" parent="#style/Theme.AppCompat.Light.DarkActionBar">
</style>
You should get ActionBar like this:
ActionBar actionBar = ((AppCompatActivity)getActivity()).getSupportActionBar();

Cannot hide/remove an Activity's title

I cannot hide the title's view from an Activity that I'm styling as a Dialog.
android:windowNoTitle is set to false in the reference style, and RequestWindowFeature(WindowFeatures.NoTitle) is called from OnCreate.
Is there another setting for completely removing the title's view from an Activity?
styles.xml
<style name="Theme.AppCompat.Light.Dialog_Configuration" parent="Theme.AppCompat.Light.Dialog">
<item name="android:windowNoTitle">true</item>
<item name="android:windowCloseOnTouchOutside">false</item>
</style>
ConfigurationView
[Activity(
Label = "Configuration",
MainLauncher = false,
Theme = "#style/Theme.AppCompat.Light.Dialog_Configuration",
ExcludeFromRecents = true
)]
public class ConfigurationView : AppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
RequestWindowFeature(WindowFeatures.NoTitle);
SetContentView(Resource.Layout.Configuration);
}
}
Are you using toolbar? You can try this
getSupportActionBar().setDisplayShowTitleEnabled(false);
or
requestWindowFeature(Window.FEATURE_NO_TITLE);//will hide the title.
getSupportActionBar().hide(); //hide the title bar.
While you have removed the title, you also need to remove the title bar as well. Try adding the following line to your onCreate method:
getSupportActionBar().hide();
Write this in the OnCreate method just after SetContentView:
ActionBar.Hide();
Alternatively, you could try this
NavigationPage.SetHasNavigationBar(this, false);

Using Activity as a Dialog in Xamarin

I am trying to use activity as a dialog, and I have done the following, but still it shows as an activity rather than dialog. I wonder what I am missing or doing wrong?
AndroidManifest.xml
<activity
android:name="AboutView"
android:theme="#style/Dialog">
</activity>
Themes.xml
<style name="Dialog" parent="#android:style/Theme.Dialog">
<item name="windowActionBar">false</item>
<item name="android:windowNoTitle">true</item>
</style>
AboutView.cs
[MvxFragment(typeof(MainViewModel), Resource.Id.MainViewContainer)]
[Activity(Label = "AboutView", Theme = "#style/Dialog")]
[Register("views.AboutView")]
public class AboutView : MvxFragment<AboutViewModel>
{
public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
var ignored = base.OnCreateView(inflater, container, savedInstanceState);
var view = this.BindingInflate(Resource.Layout.AboutView, null);
return view;
}
}
You're only specifying that the Activity's theme should inherit from Dialog's theme. The AboutView class still inherits from MVXFragment, which isn't a Dialog.
I'm not too familiar with Xamarin's class structure, but you'll need to ensure that the AboutView class inherits from Xamarin's version of a Dialog.
In Android studio it would be the DialogFragment class. You could start looking there.
I think MvxDialogFragment is exactly what you're looking for. Here you have an example how to use it

FullScreen Dialog above action bar

I have a FragmentActivity and a few fragments in my application.
In some conditions , i'll pop a dialog from activity, it will be fullscreen but it should stay below main action bar. is it possible ? ( I want to keep main action bar visible )
My Dialog Style
<style name="FullScreen" parent="#android:style/Theme.Holo.Light">
<item name="android:windowNoTitle">true</item>
<item name="android:windowFullscreen">false</item>
<item name="android:backgroundDimEnabled">false</item>
</style>
Dialog
public class FDialog extends Dialog implements OnClickListener{
Context mContext;
public FDialog(Context context) {
super(context,R.style.FullScreen);
mContext = context;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.dialog_content);
}
Thanks
After searching in the website, I found this answer that could help with your problem. It suggests to implement the Dialog with a Fragment. That way you have access to action bar easy. On the other hand, you have the disadvantage to work with the fragments flow, but it also very easy.
Hope it helps!
Show Dialog nearly full screen in my case (With ActionBar & overlay)

Android: Apply different themes to fragments of one activity

What I want to do:
I want each Fragment of my MainActivity to use a different theme, so that the ActionBar has different background-colors, depending on the visible Fragment.
The Situation:
I created a MainActivity which uses the Tabs + Swipe Navigation. I Added 7 Tabs (=7 Fragments). I created one Theme which should be applied only to the first Fragment (fragment_main_1).
Here the Theme:
<resources xmlns:android="http://schemas.android.com/apk/res/android">
<style name="Blue" parent="android:Theme.Holo.Light">
<item name="android:actionBarStyle">#style/Blue.ActionBarStyle</item>
</style>
<style name="Blue.ActionBarStyle" parent="android:Widget.Holo.Light.ActionBar">
<item name="android:titleTextStyle">#style/Blue.ActionBar.TitleTextStyle</item>
<item name="android:background">#33B5E5</item>
</style>
<style name="Blue.ActionBar.TitleTextStyle" parent="android:TextAppearance.Holo.Widget.ActionBar.Title">
<item name="android:textColor">#FFFFFF</item>
</style>
</resources>
After creating 6 more Themes it should be possible to swipe through the Tabs while the ActionBar changes its background-color automatically.
What didn't work:
Adding those lines (which I found here on stackoverflow) to the Fragment1.java:
// create ContextThemeWrapper from the original Activity Context with the custom theme
final Context contextThemeWrapper = new ContextThemeWrapper(getActivity(), R.style.Blue);
// clone the inflater using the ContextThemeWrapper
LayoutInflater localInflater = inflater.cloneInContext(contextThemeWrapper);
// inflate the layout using the cloned inflater, not default inflater
return localInflater.inflate(R.layout.fragment_main_1,container, false);
I hope you can help me:) Thank you.
Many fragments (such as PreferenceFragment) read the styled attributes directly from the Context returned by Fragment.getContext() method, so you might need to override that too:
private var themedContext: Context? = null
override fun onAttach(context: Context) {
super.onAttach(context).also {
themedContext = ContextThemeWrapper(context, R.style.ThemeForThisFragment)
// if you want to apply a theme overlay:
// themedContext.theme.applyStyle(R.style.MyThemeOverlay, true)
}
}
override fun onDetach() {
super.onDetach()
themedContext = null
}
override fun getContext(): Context? {
return themedContext ?: super.getContext()
}
Try LayoutInflater localInflater = inflater.from(contextThemeWrapper); instead.

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