Main Activity Part 2 for the Lock Screen Device App on the SSaurel's Channel

MainActivity2.java

package com.ssaurel.lockdevice;

import android.app.Activity;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

  // ...

  @Override
  public void onClick(View view) {
    if (view == lock) {
      boolean active = devicePolicyManager.isAdminActive(compName);

      if (active) {
        devicePolicyManager.lockNow();
      } else {
        Toast.makeText(this, "You need to enable the Admin Device Features", Toast.LENGTH_SHORT).show();
      }

    } else if (view == 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 we need this permission");
      startActivityForResult(intent, RESULT_ENABLE);

    } else if (view == disable) {
      devicePolicyManager.removeActiveAdmin(compName);
      disable.setVisibility(View.GONE);
      enable.setVisibility(View.VISIBLE);
    }
  }

// ...

}