错误java.lang.RuntimeException：无法启动活动ComponentInfo{com.tourism.myapplication/com.tourism.myapplication.navigationdrawer}：java.lang.NullPointerException:尝试对空对象引用调用虚拟方法“void androidx.drawerlayout.widget.DrawerLayout.addDrawerListener（androidx.drawerlayout.widget.DrawerLayout$DrawerListener）”
这是activity_navigationdrawer.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start"
    android:id="@+id/drawerLayout"
    tools:context=".MainActivity">

    <include layout="@layout/app_bar_name"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        android:id="@+id/navigationView"
        app:headerLayout="@layout/header_layout"
        app:menu="@menu/menu_item"/>

</androidx.drawerlayout.widget.DrawerLayout>

这是activity_navigationdrawer.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start"
    android:id="@+id/drawerLayout"
    tools:context=".MainActivity">

    <include layout="@layout/app_bar_name"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <com.google.android.material.navigation.NavigationView
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        android:id="@+id/navigationView"
        app:headerLayout="@layout/header_layout"
        app:menu="@menu/menu_item"/>

</androidx.drawerlayout.widget.DrawerLayout>

这是app_bar_name.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    <androidx.appcompat.widget.Toolbar
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/ttoolbar"/>

    </com.google.android.material.appbar.AppBarLayout>

    <include layout="@layout/content_main"/>

</LinearLayout>

这是活动文件

package com.tourism.myapplication;

import androidx.annotation.NonNull;
import androidx.appcompat.app.ActionBarDrawerToggle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.core.view.GravityCompat;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.MenuItem;
import android.widget.Toast;

import com.google.android.material.navigation.NavigationView;

public class navigationdrawer`your text` extends AppCompatActivity {
    DrawerLayout drawerLayout;
    NavigationView navigationView;
    Toolbar toolbar;

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

        drawerLayout = findViewById(R.id.drawerLayout);
        navigationView = findViewById(R.id.navigationView);
        toolbar = findViewById(R.id.ttoolbar);

        //step1

        setSupportActionBar(toolbar);

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawerLayout, toolbar, R.string.OpenDrawer, R.string.CloseDrawer);

        drawerLayout.addDrawerListener(toggle);

        toggle.syncState();

//       /**/ loadFragment(new homefrag());

        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                int id = item.getItemId();

                if  (id==R.id.optTrip){
                    Toast.makeText(navigationdrawer.this, "", Toast.LENGTH_SHORT).show();

                } else if (id==R.id.optHome) {
                    loadFragment(new homefrag());
                } else if (id==R.id.optAbout) {
                    Toast.makeText(navigationdrawer.this, "", Toast.LENGTH_SHORT).show();
                }else {
                    Toast.makeText(navigationdrawer.this, "", Toast.LENGTH_SHORT).show();
                }
                drawerLayout.closeDrawer(GravityCompat.START);

                return true;
            }
        });

    }

    @Override
    public void onBackPressed() {
        if (drawerLayout.isDrawerOpen(GravityCompat.START)){
            drawerLayout.closeDrawer(GravityCompat.START);
        } else{
            super.onBackPressed();
        }
    }

    private void loadFragment(Fragment fragment) {

        FragmentManager fm = getSupportFragmentManager();
        FragmentTransaction ft = fm.beginTransaction();

        ft.add(R.id.container, fragment);
        ft.commit();

    }
}

我尝试了所有的解决方案，请帮助