Android Example - Adjust Screen Brightness

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  Screen Brightness in Android can be controlled programmatically in simple way. This tutorial explains the process with an example. Native brightness control in Android device has a Seekbar that adjust the screen brightness. The below tutorial has UI in a similar way.You take a look at SeekBar tutorial here  if needed.

 android.provider.Settings.System - This class contains miscellaneous  system preferences. There are convenience functions for accessing individual system settings.

android.provider.Settings.System.getInt - Convenience function for retrieving a single system settings value as an integer. Note that internally setting values are always stored as strings; this function converts the string to an integer for you. The default value will be returned if the setting is not defined or not an integer.

android.provider.Settings.System.SCREEN_BRIGHTNESS - String that holds Screen Brightness value ranging from 0 to 255.

Get Current Screen_Brightness Value
                The above functions and constants can be used to get screen brightness as shown in the code snippet.This example  has a seekbar defined with maximum value as 255, since the screen brightness constant varies from 0 to 255.
float curBrightnessValue = 0;
curBrightnessValue=android.provider.Settings.System.getInt(getContentResolver(), android.provider.Settings.System.SCREEN_BRIGHTNESS);

The obtained value should be set to setProgress method of seekbar as shown below ,

 seekBar.setProgress(screen_brightness);

Set/Put Screen_Brightness Value 
               In the same way as get, we can also put value to set Screen_Brightness as shown in the below code snippet
android.provider.Settings.System.putInt(getContentResolver(), android.provider.Settings.System.SCREEN_BRIGHTNESS, progress);

progress is the current SeekBar progress, in this way SeekBar and Screen_Brightness will be synced.

Android Permission to Change Screen Brightness
                Since we are modifying system settings we need to add permissions in AndroidManifest.xml to modify Screen_Brightness.
<uses-permission android:name="android.permission.WRITE_SETTINGS"></uses-permission>
          
activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <SeekBar
        android:id="@+id/seekBar1"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="26dp"
        android:max="10" />
</RelativeLayout>

MainActivity.java

package com.example.android_adjustbrightness;
import android.os.Bundle;
import android.provider.Settings.SettingNotFoundException;
import android.app.Activity;
import android.view.Menu;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

public class MainActivity extends Activity {

  private SeekBar seekBar;

  @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  seekBar = (SeekBar) findViewById(R.id.seekBar1);
  seekBar.setMax(255);

   float curBrightnessValue = 0;
  try {
   curBrightnessValue = android.provider.Settings.System.getInt(
     getContentResolver(),
     android.provider.Settings.System.SCREEN_BRIGHTNESS);
  } catch (SettingNotFoundException e) {
   e.printStackTrace();
  }

   int screen_brightness = (int) curBrightnessValue;
  seekBar.setProgress(screen_brightness);
  seekBar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
   int progress = 0;

    @Override
   public void onProgressChanged(SeekBar seekBar, int progresValue,
     boolean fromUser) {
    progress = progresValue;
   }

    @Override
   public void onStartTrackingTouch(SeekBar seekBar) {
    // Do something here,
    // if you want to do anything at the start of
    // touching the seekbar
   }

    @Override
   public void onStopTrackingTouch(SeekBar seekBar) {
    android.provider.Settings.System.putInt(getContentResolver(),
      android.provider.Settings.System.SCREEN_BRIGHTNESS,
      progress);
   }
  });
 }

  @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.main, menu);
  return true;
 }

}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android_adjustbrightness"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <uses-permission android:name="android.permission.WRITE_SETTINGS" >
    </uses-permission>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.android_adjustbrightness.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Source code of this Application :
Androd_AdjustScreenBrightness.zip