How to apply new theme to whole application in android | Applying theme at run time in android

It is pretty easy to applying new theme to the whole application at run time. First you create a your own custom themes and set it in the java code. Whenever a new theme is applied at run time we have set the same before calling onCreate() and setContentView() method.
See the instructions enjoy coding....

Step-1:
Create  attrs.xml in '.../res/values' folder.


<?xml version="1.0" encoding="utf-8"?>
  <resources>
       <!-- View styles -->
       <attr name="textTitle" format="reference" />
       <attr name="textBody" format="reference" />
       <attr name="buttonText" format="reference"/>
       <attr name="radioButtonText" format="reference"/>
       <attr name="backgroundTheme" format="reference"></attr>
     
 </resources>
Step-2:

Create color.xml in values folder of you project.

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="text_color">#2B3856</color>
</resources>


Step-3:

Create styles.xml file in the '.../res/values' folder.



<?xml version="1.0" encoding="utf-8"?>
<resources>
   <style name="small_title_text">
      <item name="android:textSize">20sp</item>
      <item name="android:textColor">#228B22</item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>
   <style name="small_body_text">
      <item name="android:textSize">16sp</item>
      <item name="android:textColor"> #228B22</item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>
   <style name="small_button_text">
      <item name="android:textSize">16sp</item>
      <item name="android:textColor"> #228B22</item>
      <item name="android:textStyle">normal</item>
 
   </style>


   <style name="large_title_text">
      <item name="android:textSize">24sp</item>
      <item name="android:textColor"> #228B22</item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>

   <style name="large_body_text">
      <item name="android:textSize">20sp</item>
      <item name="android:textColor"> #228B22</item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>
   <style name="large_button_text">
      <item name="android:textSize">20sp</item>
      <item name="android:textColor"> #228B22 </item>
      <item name="android:textStyle">normal</item>

   </style>

   <!--radio button style  -->

   <style name="small_radio_btn_text">
      <item name="android:textSize">16sp</item>
      <item name="android:textColor"> #228B22 </item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>

   <style name="large_radio_btn_text">
      <item name="android:textSize">20sp</item>
      <item name="android:textColor">#228B22</item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>

   <style name="default_radio_btn_text">
      <item name="android:textSize">15sp</item>
      <item name="android:textColor"> #228B22 </item>
      <item name="android:textStyle">normal</item>
      <item name="android:paddingBottom">5dip</item>
   </style>

  <!-- Change gray_radient theme -->

  <style name="gray_gradient">
      <item name="android:background"> #C1CDCD </item>
      <item  name="android:padding">2dp</item>
</style>

  <!-- Change radial gradient theme -->

  <style name="radial_gradient">
      <item name="android:background"> #36648B </item>
      <item  name="android:padding">2dp</item>
</style>

  <style name="default_theme">
      <item name="android:background">@drawable/background</item>
      <item  name="android:padding">2dp</item>
</style>


  <!-- Change default theme -->

  <style name="background_default">
      <item name="android:background">@drawable/background</item>
      <item  name="android:padding">2dp</item>
</style>




  <!-- Base application theme is the default theme. -->
  <style name="Theme" parent="android:Theme">
  </style>

  <style name="Theme.SmallText">
     <item name="textTitle">@style/small_title_text</item>
     <item name="textBody">@style/small_body_text</item>
     <item name="buttonText">@style/small_button_text</item>
     <item name="radioButtonText">@style/small_radio_btn_text</item>
 
  </style>

  <style name="Theme.LargeText">
      <item name="textTitle">@style/large_title_text</item>
      <item name="textBody">@style/large_body_text</item>
      <item name="buttonText">@style/large_button_text</item>
      <item name="radioButtonText">@style/large_radio_btn_text</item>
  </style>

  <style name="Theme.DefaultText">
      <item name="backgroundTheme">@style/background_default</item>
      <item name="radioButtonText">@style/default_radio_btn_text</item>
  </style>

  <style name="Theme.Gray">
      <item name="backgroundTheme">@style/gray_gradient</item>
  </style>

  <style name="Theme.Radial">
      <item name="backgroundTheme">@style/radial_gradient</item>
  </style>

  <style name="Theme.DefaultTheme">
      <item name="backgroundTheme">@style/background_default</item>
  </style>

  <style name="PreferencesTheme" parent="android:Theme.Light">
       <item name="android:background">#FFEAEAEA</item>
</style>
 </resources>


Step-4:
Create  questions.xml, 
Then you need to declare you style in your xml file. 


<?xml version="1.0" encoding="utf-8"?>
<ScrollView
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="fill_parent"
 android:id="@+id/scroll_view_start_test_for_all"
 android:layout_above="@+id/lin_lay"
 android:layout_below="@+id/top"
 style="?backgroundTheme"
 android:layout_height="fill_parent">
       
           <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="10dp"
            android:paddingRight="10dp"
            android:paddingBottom="10dp"
            android:orientation="vertical">
       
     
    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:weightSum="2"
        android:layout_marginTop="10dp"
        android:orientation="horizontal">
     <TextView
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginBottom="10dp"
         android:textStyle="bold"
         style="?textBody"
         android:textColor="@color/text_color"
         android:text="Question No: "/>
     <TextView
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:layout_marginBottom="10dp"
         android:layout_weight="1.7"
         style="?textBody"
         android:textColor="@color/text_color"
         android:textStyle="bold"
         android:id="@+id/start_all_que_no"/>
   
     </LinearLayout>
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="@color/text_color"
        android:layout_marginBottom="10dp"
        style="?textBody"
        android:id="@+id/start_all_que_detail"
        android:text="@string/question"/>
   
     <RadioGroup
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:id="@+id/group_start_test_for_all"
         android:orientation="vertical">
   
      <RadioButton
       android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:textColor="@color/text_color"
          android:id="@+id/rd_option_a_start_test"
          style="?radioButtonText"
         android:text="A: LuckNow" />

       <RadioButton
       android:layout_width="wrap_content"
       android:id="@+id/rd_option_b_start_test"
       android:text="B: Agra"
       style="?radioButtonText"
       android:textColor="@color/text_color"
       android:layout_height="wrap_content"/>

       <RadioButton
       android:layout_width="wrap_content"
       android:id="@+id/rd_option_c_start_test"
       android:textColor="@color/text_color"
       android:text="C: Delhi"
       style="?radioButtonText"
       android:layout_height="wrap_content"/>

       <RadioButton
          android:layout_width="wrap_content"
          android:id="@+id/rd_option_d_start_test"
          android:text="D: Banglore"
          style="?radioButtonText"
          android:textColor="@color/text_color"
          android:layout_height="wrap_content" />
 
     </RadioGroup>
           
</LinearLayout>
   
</ScrollView>

Step-5:

Create a java file 'Utils.java' in you package res/com.example.customTheme



package com.example.com.exampe.changetheme;

import android.app.Activity;
import android.util.Log;

public class Utils {

public static String SIZE="";
public static boolean settingChanged=false;
public static String THEME="";

public static void setThemeToActivity(Activity act )
{

 try {


if (Utils.SIZE.equalsIgnoreCase("LARGE"))
{
   act.setTheme(R.style.Theme_LargeText);
   Log.d(" ", "Theme Large txt size is to be is applied.");
}
if (Utils.SIZE.equalsIgnoreCase("SMALL"))
{
   act.setTheme(R.style.Theme_SmallText);
   Log.d(" ", "Theme Small text Size is to be is applied.");
}

if(Utils.SIZE.equalsIgnoreCase("DEFAULT"))
{
act.setTheme(R.style.Theme_DefaultText);
Log.d("", "theme default text size is applied.");
}

if(Utils.THEME.equalsIgnoreCase("defaultTheme"))
{
act.setTheme(R.style.Theme_DefaultTheme);
Log.d("", "Default theme is to be applied.");
}


if(Utils.THEME.equalsIgnoreCase("Gray"))
{
act.setTheme(R.style.Theme_Gray);
Log.d("", "gray theme is to be applied.");
}

if(Utils.THEME.equalsIgnoreCase("Radial"))
{
act.setTheme(R.style.Theme_Radial);
Log.d("", "radial theme is to be applied.");
}
 

 }
 catch (Exception e) {
e.printStackTrace();
}

}
}

Step-6:

Create Activity file (CustomThemeActivity.java)  and set theme before super.onCreate() and setContentView().

package com.example.com.exampe.changetheme;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;

public class CustomThemeActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
Utils.setThemeToActivity(this);
super.onCreate(savedInstanceState);
setContentView(R.layout.questions);



}

@Override
public void onBackPressed() {
// TODO Auto-generated method stub
super.onBackPressed();
startActivity(new Intent(getBaseContext(), SettingsTheme.class));
CustomThemeActivity.this.finish();
}
}

Step-7:

Create another activity SettingTheme.java


package com.example.com.exampe.changetheme;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;

public class SettingsTheme extends Activity implements View.OnClickListener

{
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  Utils.setThemeToActivity(this);
  setContentView(R.layout.config);

  findViewById(R.id.button1).setOnClickListener(this);
  findViewById(R.id.button2).setOnClickListener(this);
  findViewById(R.id.button3).setOnClickListener(this);
 }

 public void onClick(View v)
 {
  switch (v.getId())
  {
  case R.id.button1:
      Utils.THEME="DEFAULT";
      Utils.settingChanged=true;
      Utils.SIZE="DEFAULT";
      startActivity(new Intent( SettingsTheme.this,  CustomThemeActivity.class));

   break;
  case R.id.button2:
    Utils.THEME="Gray";
    Utils.settingChanged=true;
    Utils.SIZE="SMALL";
    startActivity(new Intent( SettingsTheme.this,  CustomThemeActivity.class));
   break;
  case R.id.button3:
       Utils.THEME="Radial";
       Utils.settingChanged=true;
       Utils.SIZE="LARGE";
       startActivity(new Intent( SettingsTheme.this,  CustomThemeActivity.class));
       break;
  default :
 break;

  }

 }
     public void onBackPressed() {
  // TODO Auto-generated method stub
  super.onBackPressed();
  startActivity(new Intent( SettingsTheme.this,  CustomThemeActivity.class));
  SettingsTheme.this.finish();

 }

}

Step-8:

Create an xml for SettingActivity - config.xml


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 style="?backgroundTheme"
 android:layout_height="fill_parent">

 <LinearLayout

  android:layout_width="fill_parent"
  android:orientation="vertical"
  android:gravity="center_vertical"
  android:layout_height="fill_parent">

  <Button
   android:id="@+id/button1"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="Default with Normal Text Size"/>

  <Button
   android:id="@+id/button2"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="Gray with medium text Size"/>

  <Button
   android:id="@+id/button3"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="Radial with Large Size"/>

 </LinearLayout>

</LinearLayout>

You have almost done, run your application

These are the output when you select your theme.

You can also download the source code of this project from here : download zip.file
Hope this will help you to do well.

Regards:

Lalit