CODEWITHSUNDEEP
androidthemessharedpreferencesback-button
Ric_harvey
Ric_harvey

Reputation: 55

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

Upvotes: 0

Views: 1290

Answers (6)

Dilanka Laksiri
Dilanka Laksiri

Reputation: 268

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.

Upvotes: 0

parker_codes
parker_codes

Reputation: 3397

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!

Upvotes: 0

Abid
Abid

Reputation: 126

register onsharedpreferencechange listener in your activity

Upvotes: 0

Egor
Egor

Reputation: 40193

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.

Upvotes: 0

f20k
f20k

Reputation: 3106

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.

Upvotes: 1

Gabriel Negut
Gabriel Negut

Reputation: 13960

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.

Upvotes: 0

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