This Activity already has an action bar supplied by the window decor

[waar19]

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:3150)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3260)
at android.app.ActivityThread.access$1000(ActivityThread.java:218)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1734)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6934)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199)
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.AppCompatDelegateImplV9.setSupportActionBar(AppCompatDelegateImplV9.java:203)
at android.support.v7.app.AppCompatActivity.setSupportActionBar(AppCompatActivity.java:130)
at com.vijay.jsonwizard.activities.JsonFormActivity.onCreate(JsonFormActivity.java:38)
at android.app.Activity.performCreate(Activity.java:6609)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1134)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3103)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3260) 
at android.app.ActivityThread.access$1000(ActivityThread.java:218) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1734) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:145) 
at android.app.ActivityThread.main(ActivityThread.java:6934) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1404) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1199) 

[nooballday]

i have the same issue, did you solve it?

[AhmedHamedTN]

I think this solved the issue for me, add the following two lines in styles.xml

<item name="windowActionBar">false</item>
<item name="windowNoTitle">true</item>

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="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>
        
        <item name="windowActionBar">false</item>
        <item name="windowNoTitle">true</item>

    </style>

</resources>

Hope this helps fix the issue.

This is the Source

[shivam-codelee]

just add in this your style.xml file

<style name="AppThemeCustomized" parent="Theme.AppCompat.Light.DarkActionBar"> @color/colorPrimary @color/colorPrimaryDark @color/colorAccent false true </style>

and in manifest add

android:theme="@style/AppThemeCustomized" where you have defined your activity

[am9072]

There are two simple and quick solutions

go to res-->values-->styles
watch the simple video for the answer
https://youtu.be/YJR8njVHRA4

You can remove your window action bar by setting NoActionBar
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
or by adding false
true

[wendreof]

It worked.. a little...