Now navigate toMainActivity.java and add this code:  

package com.example.msclient010.orientationlocking;
import android.content.pm.ActivityInfo;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.CompoundButton;
import android.widget.ToggleButton;  
public class MainActivity extends ActionBarActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Get handle to the button resources
        ToggleButton toggle = (ToggleButton) findViewById(R.id.toggleButton);
        //Set default state before adding the listener
        if (getRequestedOrientation() != ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED) {
            toggle.setChecked(true);
        } else {
            toggle.setChecked(false); 
        }
        //Attach the listener to the button
        toggle.setOnCheckedChangeListener(listener);  
    } 
    CompoundButton.OnCheckedChangeListener listener = new CompoundButton.OnCheckedChangeListener() { 
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {             int current = getResources().getConfiguration().orientation;             if (!isChecked) {
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);                 return; 
            }
            switch (current) {
                case Configuration.ORIENTATION_LANDSCAPE:
                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);                     break;
                case Configuration.ORIENTATION_PORTRAIT:                     setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);                     break; 
                default:
                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED); 
                    break; 
            }
        } 
    };
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true; 
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true; 
        }
        return super.onOptionsItemSelected(item); 
    } 
} 

Code Explaination: 

·    The code in the listener is the key ingredient to this approach. If the user presses the button and it toggles to the ON state, the current orientation is read by storing the orientation parameter from Resources.getConfiguration().

·   The Configuration object and the requested orientation use different constants to map the states, so we switch on the current orientation and call setRequestedOrientation() with the appropriate constant.

·    If the user presses the button and it toggles to the OFF state, we no longer want to lock the orientation, so setRequestedOrientation() is called with the SCREEN_ORIENTATION_UNSPECIFIED constant again to return control back to the device.

·    This may also cause an immediate change to occur if the device's physical orientation differs from the activity orientation when the lock is removed. 

Running the Application:

Hit on Run button, the Emulators screen will be default showed in Portrait orientation:

Now, change the orientation to landscape, the UI will also change accordingly

Change back the orientation to portrait and click on Toggle button, the text on button will change to “LOCK” to “Locked”

Now again change the orientation to landscape mode, this time the UI will be stick to portrait orientation.

Now see how it works for Landscape mode

Change the orientation in Landscape and click on toggle button to lock the orientation

Now change the orientation to portrait mode, the UI will be locked for landscape orientation

Thanks for reading this post.

Happy Coding!! J