[android] How to change current Theme at runtime in Android

I've created a PreferenceActivity that allows the user to choose the theme he wants to apply to the entire application.

When the user selects a theme, this code is executed:

if (...) {
    getApplication().setTheme(R.style.BlackTheme);
} else {
    getApplication().setTheme(R.style.LightTheme);
}

But, even though I've checked with the debugger that the code is being executed, I can't see any change in the user interface.

Themes are defined in res/values/styles.xml, and Eclipse does not show any error.

<resources>
    <style name="LightTheme" parent="@android:style/Theme.Light">
    </style>

    <style name="BlackTheme" parent="@android:style/Theme.Black">
    </style>    
</resources>

Any idea about what could be happening and how to fix it? Should I call setTheme at any special point in the code? My application consists of several Activities if that helps.

If you want to change theme of an already existing activity, call recreate() after setTheme().

Note: don't call recreate if you change theme in onCreate(), to avoid infinite loop.

i got the same problem but i found the solution.

public class EditTextSmartPhoneActivity extends Activity implements DialogInterface.OnClickListener
{
    public final static int CREATE_DIALOG  = -1;
    public final static int THEME_HOLO_LIGHT  = 0;
    public final static int THEME_BLACK  = 1;

    int position;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        position = getIntent().getIntExtra("position", -1);

        switch(position)
        {
        case CREATE_DIALOG:
            createDialog();
            break;
        case THEME_HOLO_LIGHT:
            setTheme(android.R.style.Theme_Holo_Light);
            break;
        case THEME_BLACK:
            setTheme(android.R.style.Theme_Black);
            break;
        default:
        }

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

    }

    private void createDialog()
    {
        /** Options for user to select*/
        String choose[] = {"Theme_Holo_Light","Theme_Black"};

        AlertDialog.Builder b = new AlertDialog.Builder(this);

        /** Setting a title for the window */
        b.setTitle("Choose your Application Theme");

        /** Setting items to the alert dialog */
        b.setSingleChoiceItems(choose, 0, null);

        /** Setting a positive button and its listener */
        b.setPositiveButton("OK",this);

        /** Setting a positive button and its listener */
        b.setNegativeButton("Cancel", null);

        /** Creating the alert dialog window using the builder class */
        AlertDialog d = b.create();

        /** show dialog*/
        d.show();
    }

    @Override
    public void onClick(DialogInterface dialog, int which) {
        // TODO Auto-generated method stub
        AlertDialog alert = (AlertDialog)dialog;
        int position = alert.getListView().getCheckedItemPosition();

        finish();
        Intent intent = new Intent(this, EditTextSmartPhoneActivity.class);
        intent.putExtra("position", position);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); 
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);
    }
}

I know that i am late but i would like to post a solution here: Check the full source code here. This is the code i used when changing theme using preferences..

SharedPreferences pref = PreferenceManager
        .getDefaultSharedPreferences(this);
String themeName = pref.getString("prefSyncFrequency3", "Theme1");
if (themeName.equals("Africa")) {
    setTheme(R.style.AppTheme);
} else if (themeName.equals("Colorful Beach")) {
    //Toast.makeText(this, "set theme", Toast.LENGTH_SHORT).show();
    setTheme(R.style.beach);
} else if (themeName.equals("Abstract")) {
    //Toast.makeText(this, "set theme", Toast.LENGTH_SHORT).show();
    setTheme(R.style.abstract2);
} else if (themeName.equals("Default")) {
    setTheme(R.style.defaulttheme);
}

Instead of

getApplication().setTheme(R.style.BlackTheme);

use

setTheme(R.style.BlackTheme);

My code: in onCreate() method:

super.onCreate(savedInstanceState);

if(someExpression) {
    setTheme(R.style.OneTheme);
} else {
    setTheme(R.style.AnotherTheme);
}

setContentView(R.layout.activity_some_layout);

Somewhere (for example, on a button click):

YourActivity.this.recreate();

You have to recreate activity, otherwise - change won't happen

This had no effect for me:

public void changeTheme(int newTheme) {
    setTheme(newTheme);
    recreate();
}

But this worked:

int theme = R.style.default;

protected void onCreate(Bundle savedInstanceState) {
    setTheme(this.theme);
    super.onCreate(savedInstanceState);
}

public void changeTheme(int newTheme) {
    this.theme = newTheme;
    recreate();
}

You can finish the Acivity and recreate it afterwards in this way your activity will be created again and all the views will be created with the new theme.

I had a similar problem and I solved in this way..

@Override
public void onCreate(Bundle savedInstanceState) {

    if (getIntent().hasExtra("bundle") && savedInstanceState==null){
        savedInstanceState = getIntent().getExtras().getBundle("bundle");
    }

    //add code for theme

    switch(theme)
    {
    case LIGHT:
        setTheme(R.style.LightTheme);
        break;
    case BLACK:
        setTheme(R.style.BlackTheme);
        break;

    default:
    }
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //code

}

this code is for recreate the Activity saving Bundle and changing the theme. You have to write your own onSaveInstanceState(Bundle outState); From API-11 you can use the method recreate() instead

Bundle temp_bundle = new Bundle();
onSaveInstanceState(temp_bundle);
Intent intent = new Intent(this, MainActivity.class);
intent.putExtra("bundle", temp_bundle);
startActivity(intent);
finish();

recreate() (as mentioned by TPReal) will only restart current activity, but the previous activities will still be in back stack and theme will not be applied to them.

So, another solution for this problem is to recreate the task stack completely, like this:

    TaskStackBuilder.create(getActivity())
            .addNextIntent(new Intent(getActivity(), MainActivity.class))
            .addNextIntent(getActivity().getIntent())
            .startActivities();

EDIT:

Just put the code above after you perform changing of theme on the UI or somewhere else. All your activities should have method setTheme() called before onCreate(), probably in some parent activity. It is also a normal approach to store the theme chosen in SharedPreferences, read it and then set using setTheme() method.

Call SetContentView(Resource.Layout.Main) after setTheme().

This way work for me:

  @Override
protected void onCreate(Bundle savedInstanceState) {
    setTheme(GApplication.getInstance().getTheme());
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_main);
}

Then you want to change a new theme:

GApplication.getInstance().setTheme(R.style.LightTheme);
recreate();

This is what i have created for Material Design. May it will helpful you.

Have a look for MultipleThemeMaterialDesign

We have to set theme before calling 'super.onCreate()' and 'setContentView()' method.

Check out this link for applying new theme to whole application at runtime.