App Keeps Crashing After Trying to Add Nav Bar

Question

I've been following a tutorial to add a navigation bar to my app. However, prior to adding the relevant code, after registering the user, the user would be automatically logged in and redirected to the LoggedInMenu class. Since trying to create a navigation bar, the app crashes after clicking the register button.

My manifest file is as follows:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.XXXXXXXXX.computerscienceinduction">

<uses-permission android:name="android.permission.INTERNET" />

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".UserTypeSelection">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>
<activity android:name=".RegistrationActivity" />
<activity android:name=".LoginActivity" />
<activity android:name=".LoggedInMenu" />
<activity android:name=".GuestMenu" />
<activity android:name=".ListContacts" />
<activity
    android:name=".NavDrawerActivity"
    android:label="@string/title_activity_nav_drawer"
    android:theme="@style/AppTheme.NoActionBar"></activity>
</application>

</manifest>

My LoggedInMenu class in where I've made changes to my code to create a nav bar is as follows:

package com.example.XXXXXXXXX.computerscienceinduction;

import android.content.Intent;
import android.content.res.Configuration;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;

public class LoggedInMenu extends AppCompatActivity implements View.OnClickListener{

private FirebaseAuth firebaseAuth;

private TextView textViewUserEmail;
private Button buttonLogout;
private ListView mDrawerList;
private ArrayAdapter<String> mAdapter;
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
private String mActivityTitle;


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

    firebaseAuth = FirebaseAuth.getInstance();

    if(firebaseAuth.getCurrentUser() == null) {
        finish();
        startActivity(new Intent(this, LoginActivity.class));
    }

    FirebaseUser user = firebaseAuth.getCurrentUser();

    textViewUserEmail = (TextView) findViewById(R.id.textViewUserEmail);

    textViewUserEmail.setText("Welcome " + user.getEmail());

    buttonLogout = (Button) findViewById(R.id.buttonLogout);

    buttonLogout.setOnClickListener(this);

    mDrawerList = (ListView)findViewById(R.id.navList);

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setHomeButtonEnabled(true);

    mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);
    mActivityTitle = getTitle().toString();
}

private void addDrawerItems() {
    String[] osArray = { "Android", "iOS", "Windows", "OS X", "Linux" };
    mAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, osArray);
    mDrawerList.setAdapter(mAdapter);

    mDrawerList.setOnItemClickListener(new AdapterView.OnItemClickListener(){
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Toast.makeText(LoggedInMenu.this, "Time for an upgrade!", Toast.LENGTH_SHORT).show();
        }
    });
}

private void setupDrawer() {
    mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout,
            R.string.navigation_drawer_open, R.string.navigation_drawer_close) {

        /** Called when a drawer has settled in a completely open state. */
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            getSupportActionBar().setTitle("Navigation!");
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }

        /** Called when a drawer has settled in a completely closed state. */
        public void onDrawerClosed(View view) {
            super.onDrawerClosed(view);
            getSupportActionBar().setTitle(mActivityTitle);
            invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
        }
    };

    mDrawerToggle.setDrawerIndicatorEnabled(true);
    mDrawerLayout.setDrawerListener(mDrawerToggle);
}

@Override
public void onClick(View view) {

    if(view == buttonLogout) {
        firebaseAuth.signOut();;
        finish();
        startActivity(new Intent(this, LoginActivity.class));
    }
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    // Activate the navigation drawer toggle
    if (mDrawerToggle.onOptionsItemSelected(item)) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    // Sync the toggle state after onRestoreInstanceState has occurred.
    mDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    mDrawerToggle.onConfigurationChanged(newConfig);
}

}

The tutorial does extend ActionBarActivity rather than AppCompatActivity which I initially used when coding the login feature, but i'm not sure if that makes any difference.

Any help is appreciated, thank you.

EDIT:

After debugging, the stack trace is as follows:

E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: com.example.XXXXXXXXX.computerscienceinduction, PID: 27827
                  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.XXXXXXXXX.computerscienceinduction/com.example.XXXXXXXXX.computerscienceinduction.LoggedInMenu}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBarDrawerToggle.syncState()' on a null object reference
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3253)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3349)
                      at android.app.ActivityThread.access$1100(ActivityThread.java:221)
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
                      at android.os.Handler.dispatchMessage(Handler.java:102)
                      at android.os.Looper.loop(Looper.java:158)
                      at android.app.ActivityThread.main(ActivityThread.java:7225)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
                   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBarDrawerToggle.syncState()' on a null object reference
                      at com.example.XXXXXXXXX.computerscienceinduction.LoggedInMenu.onPostCreate(LoggedInMenu.java:135)
                      at android.app.Instrumentation.callActivityOnPostCreate(Instrumentation.java:1216)
                      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3235)
                      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3349) 
                      at android.app.ActivityThread.access$1100(ActivityThread.java:221) 
                      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:158) 
                      at android.app.ActivityThread.main(ActivityThread.java:7225) 
                      at java.lang.reflect.Method.invoke(Native Method) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)

Answer 1

您在哪里调用setupDrawer（）方法？