Lock Phone Screen Programmtically

How to lock Mobile Phone Screen ...
first of all we need to get permission from Admin
create app with default activity

Project Name : LockScreen
Package Name: com.kns
Android SDK: 2.2 API 8

the project structure is look like this

LockScreenActivity.java

  
package com.kns;


import android.app.Activity;
import android.app.ActivityManager;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class LockScreenActivity extends Activity implements OnClickListener {
 private Button lock;
 private Button disable;
 private Button enable;
 static final int RESULT_ENABLE = 1;

     DevicePolicyManager deviceManger;
     ActivityManager activityManager;
     ComponentName compName;
     
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        deviceManger = (DevicePolicyManager)getSystemService(
          Context.DEVICE_POLICY_SERVICE);
        activityManager = (ActivityManager)getSystemService(
          Context.ACTIVITY_SERVICE);
        compName = new ComponentName(this, MyAdmin.class);

        setContentView(R.layout.main);
        
        lock =(Button)findViewById(R.id.lock);
        lock.setOnClickListener(this);
        
        disable = (Button)findViewById(R.id.btnDisable);
        enable =(Button)findViewById(R.id.btnEnable);
        disable.setOnClickListener(this);
        enable.setOnClickListener(this);
    }

 @Override
 public void onClick(View v) {
  
  if(v == lock){
    boolean active = deviceManger.isAdminActive(compName);
             if (active) {
                 deviceManger.lockNow();
             }
  }
  
  if(v == enable){
   Intent intent = new Intent(DevicePolicyManager
     .ACTION_ADD_DEVICE_ADMIN);
            intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN,
                    compName);
            intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,
                    "Additional text explaining why this needs to be added.");
            startActivityForResult(intent, RESULT_ENABLE);
  }
  
  if(v == disable){
     deviceManger.removeActiveAdmin(compName);
              updateButtonStates();
  }  
 }

 private void updateButtonStates() {
  
        boolean active = deviceManger.isAdminActive(compName);
        if (active) {
            enable.setEnabled(false);
            disable.setEnabled(true);
            
        } else {
            enable.setEnabled(true);
            disable.setEnabled(false);
        }    
 }
 
  protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         switch (requestCode) {
             case RESULT_ENABLE:
                 if (resultCode == Activity.RESULT_OK) {
                     Log.i("DeviceAdminSample", "Admin enabled!");
                 } else {
                     Log.i("DeviceAdminSample", "Admin enable FAILED!");
                 }
                 return;
         }
         super.onActivityResult(requestCode, resultCode, data);
     }
}

MyAdmin.java

  
package com.kns;

import android.app.admin.DeviceAdminReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.widget.Toast;

public class MyAdmin extends DeviceAdminReceiver{


    static SharedPreferences getSamplePreferences(Context context) {
        return context.getSharedPreferences(
          DeviceAdminReceiver.class.getName(), 0);
    }

    static String PREF_PASSWORD_QUALITY = "password_quality";
    static String PREF_PASSWORD_LENGTH = "password_length";
    static String PREF_MAX_FAILED_PW = "max_failed_pw";

    void showToast(Context context, CharSequence msg) {
        Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onEnabled(Context context, Intent intent) {
        showToast(context, "Sample Device Admin: enabled");
    }

    @Override
    public CharSequence onDisableRequested(Context context, Intent intent) {
        return "This is an optional message to warn the user about disabling.";
    }

    @Override
    public void onDisabled(Context context, Intent intent) {
        showToast(context, "Sample Device Admin: disabled");
    }

    @Override
    public void onPasswordChanged(Context context, Intent intent) {
        showToast(context, "Sample Device Admin: pw changed");
    }

    @Override
    public void onPasswordFailed(Context context, Intent intent) {
        showToast(context, "Sample Device Admin: pw failed");
    }

    @Override
    public void onPasswordSucceeded(Context context, Intent intent) {
        showToast(context, "Sample Device Admin: pw succeeded");
    } 

} 

main.xml

policies.xml

AndroidManifest.xml

Before Lock the screen you need to Enable Admin Permission

Then you will get this..

 After Enable you will lock screen..like this

we have done it!!

I'd love to hear your thoughts!!