Change of themes through Java

Question

Hello! I have a java code where I would like to change the Androidmanifest themes according to the return of a certain function.

Example: Having a boolean function that checks the internet connection, the activity will use one theme when the function is true and another when the function is false.

<style name="TemaVerdadeiro" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

<style name="TemaFalso" parent="Theme.AppCompat.Light.DarkActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/branco</item>
    <item name="colorPrimaryDark">@color/branco</item>
    <item name="colorAccent">@color/ERRO</item>
</style>

Is there a command that can choose these themes according to the chosen condition?

Answer 1

To assign the theme to an Activity use the method setTheme().

Note that the new theme has to be assigned in the method onCreate() and before setContentView().

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    if(temInternet()){
        setTheme(R.style.TemaVerdadeiro);
    }
    else{
        setTheme(R.style.TemaFalso);
    }

    setContentView(R.layout.activity);

    ......
    ......

}