In many application we need to hide the title bar of Activity/Fragment Activity. For this we need to add following line in onCreate() method before calling setContentView()

requestWindowFeature(Window.FEATURE_NO_TITLE);

Example:-

public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  this.requestWindowFeature(Window.FEATURE_NO_TITLE);
  setContentView(R.layout.activity_main);
 }
}

To hide status bar from your activity, you can do this by using two ways:-
1) If you want to hide the status bar from whole application, then you can use the following theme in your manifest file:-

   android:theme="@android:style/Theme.NoTitleBar.Fullscreen" 

Example:-

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="16" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic&#95;launcher"
    android:label="@string/app&#95;name"
    android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
    <activity
        android:name="com.example.MainActivity"
        android:label="@string/app&#95;name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

2) If you want to hide a particular activity of your application, then write following line in onCreate() method before calling setContentView():-

 // If the Android version is lower than Jellybean, use this call to hide
        // the status bar.
        if (Build.VERSION.SDK_INT < 16) {
            getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN);
        }

On API level 16 or higher (i.e. Android 4.1 or higher)

View decorView = getWindow().getDecorView();
// Hide the status bar.
int uiOptions = View.SYSTEM_UI_FLAG_FULLSCREEN;
decorView.setSystemUiVisibility(uiOptions);
// Remember that you should never show the action bar if the
// status bar is hidden, so hide that too if necessary.
ActionBar actionBar = getActionBar();
actionBar.hide();

Hope you like this blog :)