Toolbar, Options Menu और Popup Menu

<!-- res/values/themes.xml: parent="Theme.Material3.DayNight.NoActionBar" -->

<com.google.android.material.appbar.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <com.google.android.material.appbar.MaterialToolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:title="My Notes" />
</com.google.android.material.appbar.AppBarLayout>

// Kotlin – in onCreate after setContentView
setSupportActionBar(binding.toolbar)

<!-- res/menu/menu_main.xml -->
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_search"
        android:icon="@drawable/ic_search"
        android:title="Search"
        app:actionViewClass="androidx.appcompat.widget.SearchView"
        app:showAsAction="ifRoom|collapseActionView" />

    <item
        android:id="@+id/action_sort"
        android:icon="@drawable/ic_sort"
        android:title="Sort"
        app:showAsAction="ifRoom" />

    <item
        android:id="@+id/action_settings"
        android:title="Settings"
        app:showAsAction="never" />

    <item
        android:id="@+id/action_about"
        android:title="About"
        app:showAsAction="never" />
</menu>

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // … binding + setSupportActionBar(binding.toolbar)

        addMenuProvider(object : MenuProvider {
            override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {
                menuInflater.inflate(R.menu.menu_main, menu)
            }
            override fun onMenuItemSelected(menuItem: MenuItem): Boolean = when (menuItem.itemId) {
                R.id.action_sort -> { showSortDialog(); true }
                R.id.action_settings -> { startActivity(Intent(this@MainActivity, SettingsActivity::class.java)); true }
                R.id.action_about -> { Toast.makeText(this@MainActivity, "Version 1.0", Toast.LENGTH_SHORT).show(); true }
                else -> false
            }
        })
    }
}

// inside onCreateMenu, after inflating
val searchView = menu.findItem(R.id.action_search).actionView as SearchView
searchView.queryHint = "Search notes…"
searchView.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
    override fun onQueryTextSubmit(query: String?): Boolean {
        searchView.clearFocus()          // hide keyboard
        return true
    }
    override fun onQueryTextChange(newText: String?): Boolean {
        adapter.submitList(allNotes.filter { it.title.contains(newText.orEmpty(), ignoreCase = true) })
        return true
    }
})

// Second activity: show ← and a title
class DetailActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityDetailBinding.inflate(layoutInflater)
        setContentView(binding.root)
        setSupportActionBar(binding.toolbar)
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
        supportActionBar?.title = "Note details"
        supportActionBar?.subtitle = "Physics"
    }
    override fun onSupportNavigateUp(): Boolean {
        finish()                          // close this screen
        return true
    }
}

<!-- res/menu/menu_note_item.xml -->
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@+id/action_edit" android:title="Edit" />
    <item android:id="@+id/action_share" android:title="Share" />
    <item android:id="@+id/action_delete" android:title="Delete" />
</menu>

// Kotlin – show it under the ⋮ button of a list row
binding.btnMore.setOnClickListener { anchor ->
    PopupMenu(anchor.context, anchor).apply {
        menuInflater.inflate(R.menu.menu_note_item, menu)
        setOnMenuItemClickListener { item ->
            when (item.itemId) {
                R.id.action_edit -> openEditor(note)
                R.id.action_share -> share(note)
                R.id.action_delete -> confirmDelete(note)
            }
            true
        }
        show()
    }
}

// From Student Diary – NotesFragment (menu only while this screen is visible)
requireActivity().addMenuProvider(object : MenuProvider {
    override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {
        menuInflater.inflate(R.menu.menu_notes, menu)
    }
    override fun onMenuItemSelected(menuItem: MenuItem) = false
}, viewLifecycleOwner, Lifecycle.State.RESUMED)