How Do I Lock Phone Programmatically Android

Ho do i lock my android phone programmatically ? I tried following this example. But when i click on the enable button the Activity pops up for few milliseconds and then closes aut

Solution 1:

You have to make your app as admin, Read something over here

Create a new empty project and create a class called MyAdminReceiver that extends DeviceAdminReceiver like this

import android.app.admin.DeviceAdminReceiver;

publicclassMyAdminReceiverextendsDeviceAdminReceiver{

}

Create a new folder called xml and create an .xml file for your admin rights called admin.xml and add the policies, in you case its locking the screen

<device-adminxmlns:android="http://schemas.android.com/apk/res/android" ><uses-policies><force-lock /></uses-policies></device-admin>

In your manifest add the receiver under Application tag

<receiverandroid:name="MyAdminReceiver"android:permission="android.permission.BIND_DEVICE_ADMIN"><meta-dataandroid:name="android.app.device_admin"android:resource="@xml/admin"/><intent-filter><actionandroid:name="android.app.action.DEVICE_ADMIN_ENABLED"/></intent-filter></receiver>

And in your MainActivity.java add code like this

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

publicclassMainActivityextendsActivityimplementsOnClickListener {

    privatestaticfinalintADMIN_INTENT=15;
    privatestaticfinalStringdescription="Some Description About Your Admin";
    private DevicePolicyManager mDevicePolicyManager; 
    private ComponentName mComponentName;  

    @OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mDevicePolicyManager = (DevicePolicyManager)getSystemService(  
                  Context.DEVICE_POLICY_SERVICE);  
        mComponentName = newComponentName(this, MyAdminReceiver.class);  
        ButtonbtnEnableAdmin= (Button) findViewById(R.id.btnEnableAdmin);
        ButtonbtnDisableAdmin= (Button) findViewById(R.id.btnDisableAdmin);
        ButtonbtnLock= (Button) findViewById(R.id.btnLock);
        btnEnableAdmin.setOnClickListener(this);
        btnDisableAdmin.setOnClickListener(this);
        btnLock.setOnClickListener(this);
    }

    @OverridepublicvoidonClick(View v) {
        switch (v.getId()) {
        case R.id.btnEnableAdmin:
            Intentintent=newIntent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
            intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, mComponentName);
            intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,description);
            startActivityForResult(intent, ADMIN_INTENT);
        break;

        case R.id.btnDisableAdmin:
            mDevicePolicyManager.removeActiveAdmin(mComponentName);  
            Toast.makeText(getApplicationContext(), "Admin registration removed", Toast.LENGTH_SHORT).show();
        break;

        case R.id.btnLock:
             booleanisAdmin= mDevicePolicyManager.isAdminActive(mComponentName);  
             if (isAdmin) {  
                 mDevicePolicyManager.lockNow();  
             }else{
                 Toast.makeText(getApplicationContext(), "Not Registered as admin", Toast.LENGTH_SHORT).show();
             }
        break;
        }
    }

    @OverrideprotectedvoidonActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == ADMIN_INTENT) {
            if (resultCode == RESULT_OK) {
                Toast.makeText(getApplicationContext(), "Registered As Admin", Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(getApplicationContext(), "Failed to register as Admin", Toast.LENGTH_SHORT).show();
            }
        }
    }

}

Note: If you try to call the Intent for Admin Device other that from an Activity subclass there are chances you might get an error to use Intent.FLAG_ACTIVITY_NEW_TASK but when you use that your window might not pop like in your case so Try opening it from a subclass of an activity only

Also you cannot un-install your app unless it has not be unregistered as an admin

Solution 2:

But when i click on the enable button the Activity pops up for few milliseconds and then closes automatically

The code shown in that sample will bring up the Settings application when clicked.

Can any one tell me how to lock the android screen

You use the code that you linked to. Here is my sample app showing the same basic thing.

Specifically:

• You need to have a BroadcastReceiver in your manifest that is set up to be a device admin component

• The user has to activate your app as a device admin

• You then call lockNow() on DevicePolicyManager

Here is the developer documentation on the device admin APIs.