Develop Reference

Dynamically show Activity as dialog

I have an Activity that I have already implemented sometime ago.
It involves around making a in app purchase, so all the logic is relatively self contained. it doesn't need to care about anything else.
Now, i wish to make that Activity to optionally show up in a dialog in some other activity. Is there a quick way to do that? I still need to keep the old behavior however, where the activity show up as a regular screen.
So is there someway that I could launch the activity with that make it show up as a dialog?
Thanks

You cant show activity as dialog.
Your options are:
1: Open the other activity with some boolean extra like "showDialog", true
Intent intent = new Intent(this, OtherActivity.class);
intent.putExtra("showDialog", true);
and in the other activity in (for example) onCreate:
Boolean showDialog = getIntent().getExtras().getBoolean("showDialog");
if (showDialog) {
// Code to show dialog
}
2: Create a DialogFragment and show it in your original activity. This custom DialogFragment you can use on both activities
https://guides.codepath.com/android/Using-DialogFragment

Probably your cleanest option depending on how complex your Activity is, is to create a new DialogFragment based on your current activity.
A DialogFragment is basically a Fragment, so has a relatively similar set of lifecycle callbacks to your Activity so it shouldn't be too difficult to re-work as a DialogFragment.
If the in-app purchase framework has specific callback requirements with an Activity then you will need to take that into account.
Another separate option would be to mock the appearance of a Dialog, by creating an Activity that may be transparent around the border of the main content.

Just Inflate the layout one button click on onCreate Method.
WhAT I WILL SUGGEST IS try alert box and in place of normal layout inflate you activity layout .
these might help

The easiest way to do that is to apply a dialog theme to the activity:
<activity android:theme="#style/Theme.AppCompat.Dialog" />
Or in the code:
#Override
protected void onCreate(Bundle savedInstanceState) {
setTheme(R.style.Theme_AppCompat_Dialog);
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
}
You can customize parameters of the theme in styles.xml, e.g. dim enabled/disabled, click outside behavior.
The crucial point is to perform setTheme() before super.onCreate(), because Theme is immutable, once set through super.onCreate() it cannot be mutated later.

Android - How to switch theme on runtime

Could someone tell me how i can switch the the theme from holo to holo light in my application on runtime ?
I would like to have two buttons in settings to choose light or black theme.
How can it be set applicationwide and not only for the activity ?
I already tried a few things with setTheme() but i wasn't able to change the theme when i click a button.
This is my Settings activity where i would like to set the theme:
public class SettingsActivity extends Activity {
#SuppressLint("NewApi")
#Override
protected void onCreate(Bundle savedInstanceState) {
setTheme(android.R.style.Theme_Holo_Light);
super.onCreate(savedInstanceState);
setContentView(R.layout.settings);
}
well this works and my Theme is set but as i am saying i would like to change it systemwide by pressing a button.
Thanks !

As you can see theme is setting on the onCreate() and before setContentView(). So you should call the oncreate() method again when you want to change the theme. But the onCreate() function will be called only once in the life cycle of an Activity.
There is a simple way to do this. I am not sure that it is the best way.
Suppose you want to apply new theme to Activity 1 on a button click.
inside the onClick event
Save the theme to be applied such that it should be retained even after the application restart (preferences or static volatile variables can be used).
Finish the current activity (Activity 1) and call a new activity (Activity 2).
Now in Activity 2
Call Activity 1 and finish current activity (Activity 2).
In Activity 1
Apply the saved theme inside onCreate.
Hope it is not confusing.. :)

You cannot change the theme of other applications (thank goodness).
The only way to somewhat accomplish this would be to create your own build of the operating system with your own theme as the device default theme. However, applications that do not use the device default theme (i.e. they explicitly set the theme to Holo, Holo light, etc) will not get the device default theme.
Edit- To accomplish this application-wide using a base Activity, create an Activity that looks like this:
public class BaseActivity extends Activity {
private static final int DEFAULT_THEME_ID = R.id.my_default_theme;
#Override
public void onCreate(Bundle savedInstanceState) {
int themeId = PreferenceManager.getDefaultSharedPreferences(context)
.getInt("themeId", DEFAULT_THEME_ID);
setTheme(themeId);
super.onCreate(savedInstanceState);
}
}
Then all of your Activities should extend this BaseActivity. When you want to change the theme, be sure to save it to your SharedPreferences.

Implementing user choice of theme

I want to give the user the choice between a few different themes, and was wondering if this is an alright way of doing things. I did a little test with this method and it worked, but I think there may be better ways and think it may cause some problems later on, so wanted to ask.
I was thinking of creating a different layout for each theme, and in onCreate just having a switch for the setContentView() method. I'd load a saved SharedPreference value (integer) first and depending on what that value was display the corresponding layout. Obviously the user could change the SharedPreference value with a button or something.
As these layouts would be basically the same but with different colours, I'd want to use the same IDs for my TextViews and other Views in each layout file. My main question is would this cause problems?
Sorry for the wall of text with no code. I'd just like to get a general idea of good practice for this situation. Thanks in advance.

I actually have this feature in my application and additionally, I allow users to change theme at runtime. As reading a value from preferences takes some time, I'm getting a theme id via globally accessible function which holds cached value.
As already pointed out - create some Android themes, using this guide. You will have at least two <style> items in your styles.xml file. For example:
<style name="Theme.App.Light" parent="#style/Theme.Light">...</style>
<style name="Theme.App.Dark" parent="#style/Theme">...</style>
Now, you have to apply one of these styles to your activities. I'm doing this in activitie's onCreate method, before any other call:
setTheme(MyApplication.getThemeId());
getThemeId is a method which returns cached theme ID:
public static int getThemeId()
{
return themeId;
}
This field is being updated by another method:
public static void reloadTheme()
{
themeSetting = PreferenceManager.getDefaultSharedPreferences(context).getString("defaultTheme", "0");
if(themeSetting.equals("0"))
themeId = R.style.Theme_Light;
else
themeId = R.style.Theme_Dark;
}
Which is being called whenever preferences are changed (and, on startup of course). These two methods reside in MyApplication class, which extends Application. The preference change listener is described at the end of this post and resides in main activity class.
The last and pretty important thing - theme is applied, when an activity starts. Assuming, you can change a theme only in preference screen and that there's only one way of getting there, i.e. from only one (main) activity, this activity won't be restarted when you will exit preference screen - the old theme still will be used. Here's the fix for that (restarts your main activity):
#Override
protected void onResume() {
super.onResume();
if(schduledRestart)
{
schduledRestart = false;
Intent i = getBaseContext().getPackageManager().getLaunchIntentForPackage( getBaseContext().getPackageName() );
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
}
scheduledRestart is a boolean variable, initially set to false. It's set to true when theme is changed by this listener, which also updates cached theme ID mentioned before:
private class ThemeListener implements OnSharedPreferenceChangeListener{
#Override
public void onSharedPreferenceChanged(SharedPreferences spref, String key) {
if(key.equals("defaultTheme") && !spref.getString(key, "0").equals(MyApplication.getThemeSetting()))
{
MyApplication.reloadTheme();
schduledRestart = true;
}
}
sp = PreferenceManager.getDefaultSharedPreferences(this);
listener = new ThemeListener();
sp.registerOnSharedPreferenceChangeListener(listener);
Remember to hold a reference to the listener object, otherwise it will be garbage colleted (and will cease to work).

If you are using Material Components themes and followed Light and Dark theme guidelines then you can do it from AppCompatDelegate. These themes can be changed/applied at run time without restarting your application.
private fun handleThemeChange(theme: String) {
when (newTheme) {
getString(R.string.light) -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
getString(R.string.dark) -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES)
getString(R.string.system) -> AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
}
}

You can also change dynamically theme using:
ContextThemeWrapper w = new ContextThemeWrapper(this, <newTHEMEId>);
getTheme().setTo(w.getTheme());
Before onCreate for each activity.

It does work if you do it this way, and I don't think it would cause any problem, but it seems like a lot of hassle (you have to multiply all your layouts by all the themes you want to add. If later you want to modify a resource in a layout, you'll have to modify it in all the themes. You're definitely bound to forget one)
Why not using the Styles and Themes feature of Android?
They can be applied to the whole activity easily:
<activity android:theme="#style/my_theme">
So that when you detect a change in the SharedPreferences value you use (button on a preference activity, or something) you can just switch the style. Or better, you can set the style to read your preference value at runtime (when creating the activity) and apply the correct style/theme accordingly.

Android Launching the current activity with different Intent Action

[Update Solution]
Referring to the post in the link
ViewPager PagerAdapter not updating the View
public void onSomeButtonClicked(View view) { // registered to Button's android:onClick in the layout xml file
Log.w(TAG,"Some button clicked !!");
getIntent().setAction(IntentManager.Intents.ACTION_SPAWN_LIST_BY_SOMETHING);
mViewPager.getAdapter().notifyDataSetChanged();
}
// And inside my PagerAdapter
#Override
public int getItemPosition(Object object) {
return 0;
}
Fixed all my problems, i just used Intent.setAction().
[Update to below Post]
My problem is i have a ViewPager PagerAdapter in my Main Activity. On clicking one of the 3 buttons., any specific intent will be fired (i used intent, i could have gone with just State variable as well, just that i pass some Uri with the intent). What happens is., i do
public void onSomeButtonClicked(View view) { // registered to Button's android:onClick in the layout xml file
Log.w(TAG,"Some button clicked !!");
getIntent().setAction(IntentManager.Intents.ACTION_SPAWN_LIST_BY_SOMETHING);
mViewPager.getAdapter().notifyDataSetChanged();
}
This is why i was guessing maybe i should just do startActivity again, with the new Intent Action on the same Activity.
Spawning a new Activity, i would have to redraw every other view in the layout which is basically the same code, for the most part in the current activity.
Any suggestions here? Please help
[Original Post]
I have a PagerAdapter and 3 Buttons in the my Main Activity. This activity is enter from Main Launcher.
When i press any one of the buttons, the Intent Action is changed.
My question:
The changed Intent action reflects some changed view in the ViewPager and does_not spawn a new Activity as such, only the view is updated.
What approach should i take to get this task?
Can i start the currentActivity using startActivity() and different Intent actions on button click?
or is there any other efficient way in android to do this?
[No need code, just explanation of logic / method would suffice]
Thanks in advance

If you are saying that you are trying to use startActivity to bring up the same activity again, and its not working, it could be because you set something like singleTop in your Android manifest.
If you are asking whether or not you should use an intent to change the state of your Activity, then the answer is "it depends". If the user would expect the back button to return your app to its previous state (instead of going back to the home screen), then it might be a good choice for you. If that is the case, however, I would ask why not just make 2 different Activities? Otherwise, just do as Dan S suggested and update the state of your Activity as the user interacts with it.

You can always use the onNewIntent() hook. Do something like this in your activity:
protected void onNewIntent(Intent intent){
//change your activity based on the new intent
}
Make sure to set the activity to singleTop in your manifest. Now whenever startActivity is called the onNewIntent() will be executed. Also, note that per the documentation:
Note that getIntent() still returns the original Intent. You can use setIntent(Intent) to update it to this new Intent.

Android SharedPreferences, themes and the back button

I have a simple activity with a theme set via setTheme(), the theme id is stored in SharedPreferences, I get this data and setTheme() before super.OnCreate() in the main activity. On pressing the menu button I can launch a preferences activity. On updating preferences and pressing the back button to return to the main activity the theme does not update to the new setting. Only closing the app and reopening fixes this.
What's the best way to make the main activity update and reload the theme after the back button is pressed in the preferences activity? I tried putting setTheme() in OnResume but to no avail.
Any help is greatly appreciated,
Thanks Ric

See this page:
According to Dianne Hackborn, Android framework engineer:
You can only set the theme during
creation. To apply a theme, the
entire UI need to be reinflated and
rebuilt from its resources.

If there is no other way, you could do something like this in your activity, after updating the preferences:
Intent i = new Intent(this, YourActivity.class);
startActivity(i);
finish();
It's not too elegant, and I do hope there is a simpler way.

and setTheme() before super.OnCreate() in the main activity
You shouldn't ever put any code before super.onCreate() or super.onResume(), all your code should be placed after these calls. Maybe this is the problem.

register onsharedpreferencechange listener in your activity

Here is the way I did it:
I have an app that has multiple themes to choose from on a page. Normally, when a theme is selected and then the back button is pressed, the theme reverts back to the previous one. This is an issue.
I used the #Override trick for onBackPressed() to do the trick. Following is the code (I also modified the code for the first activity in the stack [my Navigation Drawer]).
#Override
public void onBackPressed()
{
Intent intent1 = new Intent(this, NavigationActivity.class);
startActivity(intent1);
super.onBackPressed(); // optional depending on your needs
}
That code in the Theme Switch activity made it so the normal back button code wasn't called to destroy the current activity and revert to the old theme. It just passes to the previous activity that the user was on, which is my NavigationActivity. Customize this how you will.
Another thing to note is that the back button can still plague you even after this, because once it passes me to NavigationActivity, if I press the back button again the theme is reverted. I called the same method as before, but I took out the super.onBackPressed(); statement which is what caused the reverting. This is what it looks like:
#Override
public void onBackPressed() {
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
}
}
I hope this does the trick for you!

If you use Navigation component please try as below mentioned. It is not required to call intent or finishActivity.
override fun onBackPressed() {
when (navController.currentDestination?.id){
R.id.settingsFragment -> super.onSupportNavigateUp()
else -> super.onBackPressed()
}
}
super.onSupportNavigateUp() will be solved your back navigation problem.