Android Navigation Drawer Menu Selected Listener not working

Question

I have a navigation drawer and i intend switch activity or display a toast whenever those are clicked but i can't because my MainActivity.java seems to have problem here is my code for that

package com.example.universityportal;

import android.content.Intent;
import android.os.Bundle;
import android.text.InputFilter;
import android.text.TextUtils;
import android.view.MenuItem;
import android.view.View;
import android.view.Menu;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import com.google.android.material.navigation.NavigationView;
import com.google.android.material.textfield.TextInputEditText;

import androidx.annotation.NonNull;
import androidx.core.view.GravityCompat;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;

public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener{
TextInputEditText userName, userPassword;
Button registerBtn;
private DrawerLayout mDrawerLayout;

private AppBarConfiguration mAppBarConfiguration;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

EditText t= (EditText) findViewById(R.id.layout1);
t.setMaxLines(1);

InputFilter[] filterArray = new InputFilter[1];
filterArray[0] = new InputFilter.LengthFilter(12);
t.setFilters(filterArray);

//Defining our input fields in Java

Button button1 = (Button) findViewById(R.id.button2);
button1.setOnClickListen

Answer 1

could you post the whole code in Playground and a link to it.
mDrawerLayout is not initialized anywhere inside onCreate().
it's hard to see where the problem is without the whole code and the layouts xml.

Answer 2

Xml coming