if (!mDPM.isAdminActive(mDeviceAdminSample)) {
        // try to become active – must happen here in this activity, to get result
        Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
        intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN,mDeviceAdminSample);
        intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,"Admin is added to do security operation.");
        startActivityForResult(intent, 0);
        } else {
        // Already is a device administrator, can do security operations now.
        mDPM.lockNow();
        }

KeyguardManager manager = (KeyguardManager)context.getSystemService(KEYGUARD_SERVICE);
kl = manager.newKeyguardLock("my-remote-app");
kl.disableKeyguard();

onDestroy() {
kl.reenableKeyguard();
}