Setting up a Toolbar

activity_main.xml

<androidx.appcompat.widget.Toolbar
        android:id="@+id/my_toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        android:elevation="4dp"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

build.gradle

dependencies {
...

    implementation 'androidx.appcompat:appcompat:1.4.1'


}

Description.md

In the begging android had the Action Bar as an App bar (that's why remove on the manifest) but more features were added to the Toolbar. available now in this library. 'androidx.appcompat:appcompat:1.4.1'

MainActivity.kt

class MainActivity : AppCompatActivity() {

  override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_my)
      // Note that the Toolbar defined in the layout has the id "my_toolbar"
      setSupportActionBar(findViewById(R.id.my_toolbar))
  }

}

MainActivityWithMenu.kt

        supportActionBar?.title = "Title"
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
    }

    override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.menu_actiobar, menu)
        return super.onCreateOptionsMenu(menu)
    }

    override fun onOptionsItemSelected(item: MenuItem) = when (item.itemId) {
        R.id.action_favorite -> {
            Toast.makeText(this@MainActivity, "ayayay", Toast.LENGTH_LONG).show()
            true
        }
        else -> {
            super.onOptionsItemSelected(item)
        }
    }

manifest.xml

<application
        android:theme="@style/Theme.AppCompat.Light.NoActionBar"
        android:allowBackup="true"

menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_favorite"
        android:icon="@drawable/ic_launcher_background"
        android:title="item"
        app:showAsAction="ifRoom"/>

</menu>