NullPointerException When starting new Activity in Navigation Drawer
<p>I am using a template navigation drawer that was provided by android studio. I am very new to android development so i'm wondering if i'm missing something simple here. I want to start a new activity by clicking on an item in  my navigation menu I followed several tutorials on how to do this but i keep getting this error in my logcat:</p>

<pre><code>java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.bsmyth.sidemenu/com.example.bsmyth.sidemenu.second_activity}: java.lang.NullPointerException
</code></pre>

<p>Here is the code I tried to start a new activity:</p>

<pre><code>@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_camera) {
        // Handle the camera action
    } 

    else if (id == R.id.nav_gallery) {
        Intent intent = new Intent(MainActivity.this, second_activity.class);
        startActivity(intent);
    } 

      else if (id == R.id.nav_slideshow) {

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}
</code></pre>

<p>I referred to my second activity in my manifest file like this:
    
    </p>

<pre><code>&lt;application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"&gt;
    &lt;activity
        android:name=".MainActivity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme.NoActionBar"&gt;
        &lt;intent-filter&gt;
            &lt;action android:name="android.intent.action.MAIN" /&gt;

            &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
        &lt;/intent-filter&gt;
    &lt;/activity&gt;
    &lt;activity android:name=".second_activity"&gt;
        &lt;intent-filter&gt;
            &lt;action android:name="com.example.bsmyth.sidemenu.second_activity" /&gt;

            &lt;category android:name="android.intent.category.DEFAULT" /&gt;
        &lt;/intent-filter&gt;
    &lt;/activity&gt;
&lt;/application&gt;
</code></pre>

<p></p>

<p>Here is the drawer layout:</p>

<pre><code>&lt;group android:checkableBehavior="single"&gt;
    &lt;item
        android:id="@+id/nav_camera"
        android:icon="@drawable/ic_menu_camera"
        android:title="Adfeed"
        android:checked="true"/&gt;
    &lt;item
        android:id="@+id/nav_gallery"
        android:icon="@drawable/ic_menu_gallery"
        android:title="Post" /&gt;
    &lt;item
        android:id="@+id/nav_slideshow"
        android:icon="@drawable/ic_menu_slideshow"
        android:title="Notification" /&gt;
    &lt;item
        android:id="@+id/nav_manage"
        android:icon="@drawable/ic_menu_send"
        android:title="Messages" /&gt;
&lt;/group&gt;
</code></pre>

<p>Here is the second activity:</p>

<pre><code>package com.example.bsmyth.sidemenu;

import android.app.ActionBar;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;

public class second_activity extends AppCompatActivity
            implements NavigationView.OnNavigationItemSelectedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second_activity);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @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;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_camera) {
            // Handle the camera action
        } else if (id == R.id.nav_gallery) {

        } else if (id == R.id.nav_slideshow) {

        } else if (id == R.id.nav_manage) {

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}
</code></pre>

<p>Here is second_activity layout:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;android.support.v4.widget.DrawerLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"&gt;

&lt;TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Your in the second activity"
    android:textSize="20sp"/&gt;

&lt;/android.support.v4.widget.DrawerLayout&gt;
</code></pre>

<p>And here are the error messages in logcat:</p>

<pre><code>java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.bsmyth.sidemenu/com.example.bsmyth.sidemenu.second_activity}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
    at android.app.ActivityThread.access$600(ActivityThread.java:130)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:4745)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
    at com.example.bsmyth.sidemenu.second_activity.onCreate(second_activity.java:30)
    at android.app.Activity.performCreate(Activity.java:5008)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
    at android.app.ActivityThread.access$600(ActivityThread.java:130) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
    at android.os.Handler.dispatchMessage(Handler.java:99) 
    at android.os.Looper.loop(Looper.java:137) 
    at android.app.ActivityThread.main(ActivityThread.java:4745) 
    at java.lang.reflect.Method.invokeNative(Native Method) 
    at java.lang.reflect.Method.invoke(Method.java:511) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
    at dalvik.system.NativeStart.main(Native Method) 
</code></pre>