Toast, Snackbar और Dialogs

Toast.makeText(this, "Note saved", Toast.LENGTH_SHORT).show()          // in an Activity
Toast.makeText(requireContext(), R.string.saved, Toast.LENGTH_LONG).show() // in a Fragment

// From Student Diary – swipe to delete with UNDO
viewModel.delete(note)
Snackbar.make(binding.root, "\"${note.title}\" deleted", Snackbar.LENGTH_LONG)
    .setAction("Undo") { viewModel.restore(note) }
    .show()

// show it above a FAB / bottom navigation
Snackbar.make(binding.root, "No internet", Snackbar.LENGTH_INDEFINITE)
    .setAnchorView(binding.fab)
    .setAction("Retry") { loadData() }
    .show()

MaterialAlertDialogBuilder(this)
    .setTitle("Delete note?")
    .setMessage("\"Maths homework\" will be deleted permanently.")
    .setIcon(R.drawable.ic_delete)
    .setNegativeButton("Cancel", null)                        // just closes
    .setPositiveButton("Delete") { dialog, _ ->
        deleteNote()
        dialog.dismiss()
    }
    .show()

// simple list
val actions = arrayOf("Edit", "Share", "Delete")
MaterialAlertDialogBuilder(this)
    .setTitle("Note options")
    .setItems(actions) { _, which ->
        Toast.makeText(this, actions[which], Toast.LENGTH_SHORT).show()
    }
    .show()

// single choice (radio buttons)
val themes = arrayOf("Light", "Dark", "System default")
var selected = 2
MaterialAlertDialogBuilder(this)
    .setTitle("Choose theme")
    .setSingleChoiceItems(themes, selected) { _, which -> selected = which }
    .setPositiveButton("Apply") { _, _ -> applyTheme(selected) }
    .setNegativeButton("Cancel", null)
    .show()

// multi choice
val subjects = arrayOf("Maths", "Physics", "Chemistry")
val checked = booleanArrayOf(true, false, false)
MaterialAlertDialogBuilder(this)
    .setTitle("Subjects")
    .setMultiChoiceItems(subjects, checked) { _, which, isChecked -> checked[which] = isChecked }
    .setPositiveButton("OK", null)
    .show()

<!-- res/layout/dialog_rename.xml -->
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingHorizontal="24dp"
    android:paddingTop="8dp">

    <com.google.android.material.textfield.TextInputLayout
        android:id="@+id/tilName"
        style="@style/Widget.Material3.TextInputLayout.OutlinedBox"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Subject name">

        <com.google.android.material.textfield.TextInputEditText
            android:id="@+id/etName"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </com.google.android.material.textfield.TextInputLayout>
</FrameLayout>

val dialogBinding = DialogRenameBinding.inflate(layoutInflater)
MaterialAlertDialogBuilder(this)
    .setTitle("Add subject")
    .setView(dialogBinding.root)
    .setNegativeButton("Cancel", null)
    .setPositiveButton("Add") { _, _ ->
        val name = dialogBinding.etName.text?.toString()?.trim().orEmpty()
        if (name.isNotEmpty()) addSubject(name)
    }
    .show()

// res/layout/sheet_sort.xml has three TextViews: tvNewest, tvPriority, tvTitle
val sheet = BottomSheetDialog(this)
val sheetBinding = SheetSortBinding.inflate(layoutInflater)
sheet.setContentView(sheetBinding.root)
sheetBinding.tvNewest.setOnClickListener { sortBy("newest"); sheet.dismiss() }
sheetBinding.tvPriority.setOnClickListener { sortBy("priority"); sheet.dismiss() }
sheetBinding.tvTitle.setOnClickListener { sortBy("title"); sheet.dismiss() }
sheet.show()