Train of thought:
Enter the account password to log in, enter the main page, click the forced logoff button on the main page, and issue the forced logoff broadcast in the button event. Implement the broadcast receiver in BaseActivity, destroy all activities in the broadcast receiver, and then restart the login interface.
However, the forced logoff function needs to be implemented in every activity interface, so we need to implement the registration and logout of broadcast receivers in every activity. In this way, no matter when the system sends the forced offline broadcast, we can receive the broadcast and realize the forced offline function. The best way to achieve this is to register and unregister the broadcast in the onResume() and onPause() methods of BaseActivity.

Source code address of the first line of code (Guo Lin)

BaseActivity code is as follows

public class BaseActivity extends AppCompatActivity {

    private ForceOfflineReceiver receiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ActivityCollector.addActivity(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.broadcastbestpractice.FORCE_OFFLINE");
        receiver = new ForceOfflineReceiver();
        registerReceiver(receiver, intentFilter);//Register broadcast receiver
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (receiver != null) {
            unregisterReceiver(receiver);//Unregister broadcast receiver
            receiver = null;
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ActivityCollector.removeActivity(this);
    }

    class ForceOfflineReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(final Context context, Intent intent) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context);//Build a dialog
            builder.setTitle("Warning");
            builder.setMessage("You are forced to be offline. Please try to login again.");
            builder.setCancelable(false);//Dialog set to non cancelable
            builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {//Set OK button for dialog box
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    ActivityCollector.finishAll(); // Destroy all activities
                    Intent intent = new Intent(context, LoginActivity.class);
                    context.startActivity(intent); // Restart LoginActivity
                }
            });
            builder.show();
        }

    }

}

LoginActivity code is as follows

public class LoginActivity extends BaseActivity {

    private EditText accountEdit;

    private EditText passwordEdit;

    private Button login;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        accountEdit=(EditText) findViewById(R.id.account);
        passwordEdit=(EditText) findViewById(R.id.password);
        login = (Button) findViewById(R.id.login);
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String account=accountEdit.getText().toString();
                String password=passwordEdit.getText().toString();
                //If the account is admin and 123456, the login is successful
                if (account.equals("admin") && password.equals("123456")) {
                    Intent intent = new Intent(LoginActivity.this, MainActivity.class);
                    startActivity(intent);
                    finish();
                } else {
                    Toast.makeText(LoginActivity.this,"account or password is invalid",Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

MainActivity code is as follows

public class MainActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button forceOffline = (Button) findViewById(R.id.force_offline);
        forceOffline.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent =new Intent("com.example.broadcastbestpractice.FORCE_OFFLINE");
                sendBroadcast(intent);
            }
        });
    }
}