Android app adding toolbar causes exception - android-studio

Question

I thought I should add a toolbar as I'll need a settings button.
So I added this to my main_activity.xml
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:title="PSA MFD"
app:subtitle="Multi functional display for Citroen and Peugeot"
app:logo="#android:drawable/ic_menu_call"
app:navigationIcon="#drawable/ic_fan"
/>
But now my app won't run because:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rwb.psamfd/com.rwb.psamfd.MainActivity}: android.view.InflateException: Binary XML file line #10: Binary XML file line #10: Error inflating class android.support.v7.widget.Toolbar
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: android.view.InflateException: Binary XML file line #10: Binary XML file line #10: Error inflating class android.support.v7.widget.Toolbar
Caused by: android.view.InflateException: Binary XML file line #10: Error inflating class android.support.v7.widget.Toolbar
Caused by: java.lang.ClassNotFoundException: Didn't find class "android.support.v7.widget.Toolbar" on path: DexPathList[[zip file "/data/app/com.rwb.psamfd-2/base.apk"],nativeLibraryDirectories=[/data/app/com.rwb.psamfd-2/lib/x86, /system/lib, /vendor/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
at android.view.LayoutInflater.createView(LayoutInflater.java:609)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:787)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
at android.view.LayoutInflater.inflate(LayoutInflater.java:377)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:555)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:161)
at com.rwb.psamfd.MainActivity.onCreate(MainActivity.kt:31)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
What do I ned to do? I have absolutely no idea. (I'm new to Android development -- and it's very difficult compared to C#).

Answer 1

Method 1:
Add the following to your dependencies in build.gradle file:
dependencies {
...
**implementation 'androidx.appcompat:appcompat:1.0.0'**
}
And change your toolbar as:
<androidx.appcompat.widget.Toolbar
....
Your contents
....>
<androidx.appcompat.widget.Toolbar/>
Method 2:
You can migrate to androidx directly.
Hope you will find the solution.