Theme Action Bar Error When Trying To Navigate To Activity

Question

Hello I have the following activity_main.xml file:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    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"
    android:id="@+id/coordinatorLayout"
    tools:context="com.xxxxxx.eventmanager.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_height="wrap_content"
        android:layout_width="match_parent"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay" />

    </android.support.design.widget.AppBarLayout>

    <ListView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/eventListView"
        android:layout_centerHorizontal="true" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@android:drawable/ic_dialog_email" />

</android.support.design.widget.CoordinatorLayout>

With the following ActivityMain.java class:

package com.xxxxxx.eventmanager;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.app.Activity;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Toast;

import com.xxxxxx.eventmanager.models.UpdaterModel;
import com.xxxxxx.eventmanager.services.UpdaterService;

public class MainActivity extends AppCompatActivity {

    // Shared Preferences
    private SharedPreferences settings;
    public static Context contextOfApplication;
    private UpdaterModel mUpdater;

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

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        settings = getSharedPreferences("App", MODE_PRIVATE);

        Intent ishintent = new Intent(this, UpdaterService.class);
        PendingIntent pintent = PendingIntent.getService(this, 0, ishintent, 0);
        AlarmManager alarm = (AlarmManager)getSystemService(this.ALARM_SERVICE);
        alarm.cancel(pintent);
        alarm.setRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), 10000, pintent);

        contextOfApplication = getApplicationContext();

        mUpdater = new UpdaterModel(this);

    }

    @Override
    protected void onResume() {
        super.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.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
        switch (id) {
            case R.id.action_settings:
                Toast.makeText(MainActivity.this, "You selected the settings menu!", Toast.LENGTH_SHORT).show();
                return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public void logEventsTask (View view) {
        Log.i("events", mUpdater.getEventData().toString());
    }

    public static Context getContextOfApplication(){
        return contextOfApplication;
    }

}

Now when I try to navigate to this activity from my LoginActivity like this:

Intent i = new Intent(LoginActivity.this, MainActivity.class);
LoginActivity.this.startActivity(i);

Along comes this error:

FATAL EXCEPTION: main
     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xxxxxx.eventmanager/com.xxxxxx.eventmanager.MainActivity}: java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
         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.IllegalStateException: This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_SUPPORT_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.
         at android.support.v7.app.AppCompatDelegateImplV7.setSupportActionBar(AppCompatDelegateImplV7.java:198)
         at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:99)
         at com.xxxxxx.eventmanager.MainActivity.onCreate(MainActivity.java:34)
         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)

I am new to Java and Android programming so I'm having trouble with this and do not currently have an idea of how to solve this issue.

This is my styles.xml file:

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
    <style name="AppTheme.NoActionBar">
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>
    </style>
    <style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />
    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
</resources>

Answer 1

The error says:

java.lang.IllegalStateException: This Activity already has an action bar supplied by the window decor.

Thus, since you use the appcompat toolbar, in your android manifest activity tag, you should specify it like this:

<manifest>
    ...
    <application>
        ....
        <activity 
            android:name="com.xxxxxx.eventmanager.MainActivity"
            android:theme="@style/AppTheme.NoActionBar"/>

    </application>
</manifest>

Answer 2

The theme which you are using already has an action bar with it and also you are trying to set your toolbar as action bar using

setSupportActionBar(toolbar);

which is causing the error.

If you want to use your toolbar as ActionBar use

Theme.AppCompat.Light.NoActionBar

as parent in your theme