java - Android - Change app Theme on onClick

Question

This question already has answers here:

Answer 1

Following blog can solve your problem:

http://mrbool.com/how-to-change-the-layout-theme-of-an-android-application/25837

Copying the blog code for quick reference:

Assuming that you already defined following three themes in the XML file R.style.FirstTheme, R.style.SecondTheme and R.style.ThirdTheme

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
public class ChangeThemeActivity extends Activity implements OnClickListener
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        Utils.onActivityCreateSetTheme(this);
        setContentView(R.layout.main);

                    findViewById(R.id.button1).setOnClickListener(this);
          findViewById(R.id.button2).setOnClickListener(this);
          findViewById(R.id.button3).setOnClickListener(this);
    }
     @Override
     public void onClick(View v)
     {
          // TODO Auto-generated method stub
          switch (v.getId())
          {
          case R.id.button1:
          Utils.changeToTheme(this, Utils.THEME_DEFAULT);
          break;
          case R.id.button2:
          Utils.changeToTheme(this, Utils.THEME_WHITE);
          break;
          case R.id.button3:
          Utils.changeToTheme(this, Utils.THEME_BLUE);
          break;
          }
     }
}

Let us write the below code in the "Utils" file:

import android.app.Activity;
import android.content.Intent;
public class Utils
{
     private static int sTheme;
     public final static int THEME_DEFAULT = 0;
     public final static int THEME_WHITE = 1;
     public final static int THEME_BLUE = 2;
     /**
      * Set the theme of the Activity, and restart it by creating a new Activity of the same type.
      */
     public static void changeToTheme(Activity activity, int theme)
     {
          sTheme = theme;
          activity.finish();
activity.startActivity(new Intent(activity, activity.getClass()));
     }
     /** Set the theme of the activity, according to the configuration. */
     public static void onActivityCreateSetTheme(Activity activity)
     {
          switch (sTheme)
          {
          default:
          case THEME_DEFAULT:
              activity.setTheme(R.style.FirstTheme);
              break;
          case THEME_WHITE:
              activity.setTheme(R.style.SecondTheme);
              break;
          case THEME_BLUE:
              activity.setTheme(R.style.Thirdheme);
              break;
          }
     }
}

Hope it helps...

EDIT 1:

following is the reason AlertDialog does not take custom theme:

Implementation in Builder.create() is:

public AlertDialog create() {
    final AlertDialog dialog = new AlertDialog(P.mContext);
    P.apply(dialog.mAlert);
    [...]
}

which calls the "not-theme-aware" constructor of AlertDialog, which looks like this:

protected AlertDialog(Context context) {
    this(context, com.android.internal.R.style.Theme_Dialog_Alert);
}

There is a second constructor in AlertDialog for changing themes:

protected AlertDialog(Context context, int theme) {
    super(context, theme);
    [...]
}

that the Builder just doesn't call.

Check out following post for more relevant fixes..

How to change theme for AlertDialog

Following is the most voted answer:

  new AlertDialog.Builder(
  new ContextThemeWrapper(context, android.R.style.Theme_Dialog))