MOBILE APPLICATION DEVELOPMENT (MAD): LAB 6
Lab 06
Activities
Activity 1:
In this task, your goal is to build a straightforward Android application with two activities. The
primary objective is to create a login system. The first activity will serve as a login screen,
prompting users to input their username and password. A "Login" or "Sign In" button should
accompany these fields. When users submit their credentials, the app will verify them against a
predefined record in an SQLite database. If the credentials match, users will be taken to the
second activity. If not, an error message in red text will inform them of the issue.
In the second activity, you will create a greeting screen, featuring a simple TextView with a
message like "Hello, [username]," where "[username]" will display the actual username entered
during login or retrieved from the database. Moreover, your app should remember the user's
login state. If a user successfully logs in, the app should remember this and not require them to
log in again when they close and reopen the app. Additionally, implement a "Log Out" or "Sign
Out" button in the second activity. When tapped, this button should return the user to the login
screen (Activity 1). If the user closes and reopens the app, they should see the login screen to
proceed to the second activity once more.
Kotlin Codes:
(Main Activity)
package com.example.myapplication
import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import androidx.core.content.ContextCompat
class MainActivity : AppCompatActivity() {
private lateinit var sharedPreferences: SharedPreferences
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
sharedPreferences = getSharedPreferences("MyPrefs",
Context.MODE_PRIVATE)
val
val
val
val
usernameEditText = findViewById<EditText>(R.id.usernameEditText)
passwordEditText = findViewById<EditText>(R.id.passwordEditText)
loginButton = findViewById<Button>(R.id.loginButton)
errorMessage = findViewById<TextView>(R.id.errorTextView)
loginButton.setOnClickListener {
val username = usernameEditText.text.toString()
val password = passwordEditText.text.toString()
if (isValidCredentials(username, password)) {
saveLoginState(true)
val intent = Intent(this, GreetingActivity::class.java)
intent.putExtra("username", username)
startActivity(intent)
finish()
} else {
errorMessage.apply {
text = "Invalid username or password"
setTextColor(ContextCompat.getColor(this@MainActivity,
R.color.errorRed))
visibility = TextView.VISIBLE
}
}
}
}
private fun isValidCredentials(username: String, password: String):
Boolean {
return (username == "admin" && password == "password")
}
private fun saveLoginState(isLoggedIn: Boolean) {
val editor = sharedPreferences.edit()
editor.putBoolean("isLoggedIn", isLoggedIn)
editor.apply()
}
}
(Greeting)
package com.example.myapplication
import
import
import
import
import
import
import
import
android.content.Context
android.content.Intent
android.content.SharedPreferences
android.os.Bundle
android.widget.Button
android.widget.EditText
android.widget.TextView
androidx.appcompat.app.AppCompatActivity
class GreetingActivity : AppCompatActivity() {
private lateinit var sharedPreferences: SharedPreferences
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_greeting)
sharedPreferences = getSharedPreferences("MyPrefs",
Context.MODE_PRIVATE)
val logoutButton : Button = findViewById(R.id.logoutButton)
val greetingTextView : TextView = findViewById(R.id.greetingTextView)
val username = intent.getStringExtra("username")
greetingTextView.text = "Hello, $username!"
logoutButton.setOnClickListener {
// Clear login state
sharedPreferences.edit().putBoolean("isLoggedIn", false).apply()
// Navigate back to login activity
val intent = Intent(this, MainActivity::class.java)
startActivity(intent)
finish()
}
}
}
XML Layout codes:
Xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<EditText
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="Enter Username"
android:ems="10"
android:inputType="textPersonName"
tools:layout_editor_absoluteX="56dp"
tools:layout_editor_absoluteY="262dp" />
<EditText
android:id="@+id/password"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:hint="Enter Password"
android:inputType="textPassword"
tools:layout_editor_absoluteX="56dp"
tools:layout_editor_absoluteY="307dp" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Login"
tools:layout_editor_absoluteX="127dp"
tools:layout_editor_absoluteY="352dp" />
<ImageButton
android:id="@+id/imageButton2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@drawable/img_1"
tools:layout_editor_absoluteX="16dp"
tools:layout_editor_absoluteY="16dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
(Greeting xml)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp"
tools:context=".GreetingActivity">
<TextView
android:id="@+id/greetingTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="20sp" />
<Button
android:id="@+id/logoutButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Log Out" />
</LinearLayout>
Activity 2:
In this task, you will be creating a straightforward To-Do app. The main screen of the app will
display a title at the top, saying "To-Do's," followed by an empty list (a ListView below the
TextView). This list will show all your To-Do items, which will be stored in an SQLite database.
Initially, the list and database will be empty.
To add a To-Do item, you should add a "+" icon in the app's Toolbar. When you tap this icon, a
dialog box should pop up, presenting you with an editable text field to type your new To-Do. Two
buttons, labeled "Add" and "Cancel," should be available in this dialog. If you click "Cancel,"
nothing should change, and the dialog box should disappear. But if you select "Add," your new
To-Do should be saved in the database, and the dialog should close. The list should then refresh
to include both your existing To-Dos (if any) and the newly added one.
For editing an existing To-Do, you should long-press on the item you wish to modify. A context
menu should appear with an "Edit" option. When you choose this option, another dialog box
should appear with an editable text field containing the text of the selected To-Do. Similar to the
previous dialog, there should be two buttons, "Save" and "Cancel." If you click "Cancel," nothing
should change, and the dialog box should close. However, selecting the "Save" button should
update the To-Do in the database, close the dialog, and refresh the list to show/load the updated
To-Do's from the database (even the edited To-Do in its new/edited form).
Xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">
<androidx.appcompat.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
android:theme="?attr/actionBarTheme" />
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="@+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end"
android:layout_margin="16dp"
android:src="@android:drawable/ic_input_add" />
</LinearLayout>
Kotlin
package com.example.myapplication
import android.os.Bundle
import android.widget.EditText
import android.widget.ListView
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.floatingactionbutton.FloatingActionButton
class MainActivity : AppCompatActivity() {
private lateinit var dbHelper: DatabaseHelper
private lateinit var todoAdapter: TodoAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
dbHelper = DatabaseHelper(this)
todoAdapter = TodoAdapter(this, dbHelper.getAllTodos())
val listView = findViewById<ListView>(R.id.listView)
val fab = findViewById<FloatingActionButton>(R.id.fab)
listView.adapter = todoAdapter
fab.setOnClickListener {
showAddTodoDialog()
}
listView.setOnItemLongClickListener { _, _, position, _ ->
showEditTodoDialog(position)
true
}
}
private fun showAddTodoDialog() {
val editText = EditText(this)
val dialog = AlertDialog.Builder(this)
.setTitle("Add New Todo")
.setView(editText)
.setPositiveButton("Add") { _, _ ->
val todoText = editText.text.toString()
if (todoText.isNotEmpty()) {
dbHelper.addTodoItem(todoText)
refreshTodoList()
}
}
.setNegativeButton("Cancel", null)
.create()
dialog.show()
}
private fun showEditTodoDialog(position: Int) {
val selectedTodo = todoAdapter.getItem(position)
val editText = EditText(this)
if (selectedTodo != null) {
editText.setText(selectedTodo.todoText)
}
val dialog = AlertDialog.Builder(this)
.setTitle("Edit Todo")
.setView(editText)
.setPositiveButton("Save") { _, _ ->
val updatedTodoText = editText.text.toString()
if (updatedTodoText.isNotEmpty()) {
if (selectedTodo != null) {
dbHelper.updateTodoItem(selectedTodo.id,
updatedTodoText)
}
refreshTodoList()
}
}
.setNegativeButton("Cancel", null)
.create()
dialog.show()
}
private fun refreshTodoList() {
val newTodos = dbHelper.getAllTodos()
todoAdapter.updateList(newTodos)
}
}
package com.example.myapplication
import
import
import
import
import
import
import
android.annotation.SuppressLint
android.app.Activity
android.content.Intent
android.os.Bundle
android.widget.Button
android.widget.EditText
androidx.appcompat.app.AppCompatActivity
class AddToDoActivity : AppCompatActivity() {
@SuppressLint("MissingInflatedId")
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_add_to_do)
val addTodoButton: Button = findViewById(R.id.addTodoButton)
val cancelButton: Button = findViewById(R.id.cancelButton)
val todoEditText: EditText = findViewById(R.id.todoEditText)
addTodoButton.setOnClickListener {
val todoText = todoEditText.text.toString()
val resultIntent = Intent()
resultIntent.putExtra("newTodo", todoText)
setResult(Activity.RESULT_OK, resultIntent)
finish()
}
cancelButton.setOnClickListener {
finish()
}
}
}
package com.example.myapplication
// DatabaseHelper.kt
import android.annotation.SuppressLint
import android.content.ContentValues
import android.content.Context
import android.database.Cursor
import android.database.SQLException
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
class DatabaseHelper(context: Context) :
SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {
companion object {
private const val
private const val
private const val
private const val
private const val
}
DATABASE_NAME = "todo_database"
DATABASE_VERSION = 1
TABLE_TODO = "todo"
KEY_ID = "id"
KEY_TEXT = "todo_text"
override fun onCreate(db: SQLiteDatabase) {
val CREATE_TODO_TABLE = ("CREATE TABLE $TABLE_TODO($KEY_ID INTEGER
PRIMARY KEY, $KEY_TEXT TEXT)")
db.execSQL(CREATE_TODO_TABLE)
}
override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion:
Int) {
db.execSQL("DROP TABLE IF EXISTS $TABLE_TODO")
onCreate(db)
}
fun addTodoItem(todoText: String) {
val values = ContentValues()
values.put(KEY_TEXT, todoText)
val db = this.writableDatabase
db.insert(TABLE_TODO, null, values)
db.close()
}
fun updateTodoItem(id: Int, updatedText: String) {
val values = ContentValues()
values.put(KEY_TEXT, updatedText)
val db = this.writableDatabase
db.update(TABLE_TODO, values, "$KEY_ID=?", arrayOf(id.toString()))
db.close()
}
@SuppressLint("Range")
fun getAllTodos(): List<TodoItem> {
val todoList = mutableListOf<TodoItem>()
val query = "SELECT * FROM $TABLE_TODO"
val db = this.readableDatabase
try {
val cursor: Cursor = db.rawQuery(query, null)
if (cursor.moveToFirst()) {
do {
val id = cursor.getInt(cursor.getColumnIndex(KEY_ID))
val text =
cursor.getString(cursor.getColumnIndex(KEY_TEXT))
val todoItem = TodoItem(id, text)
todoList.add(todoItem)
} while (cursor.moveToNext())
}
} catch (e: SQLException) {
e.printStackTrace()
}
db.close()
return todoList
}
}
// TodoItem.kt
data class TodoItem(val id: Int, val todoText: String)
package com.example.myapplication
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ArrayAdapter
import android.widget.TextView
class TodoAdapter(context: Context, private var todoList: List<TodoItem>) :
ArrayAdapter<TodoItem>(context, 0, todoList) {
override fun getView(position: Int, convertView: View?, parent:
ViewGroup): View {
var convertView = convertView
if (convertView == null) {
convertView =
LayoutInflater.from(context).inflate(android.R.layout.simple_list_item_1,
parent, false)
}
val todoItem = getItem(position)
val textView =
convertView!!.findViewById<TextView>(android.R.id.text1)
textView.text = todoItem?.todoText
return convertView
}
fun updateList(newList: List<TodoItem>) {
todoList.run {
clear()
addAll(newList)
}
}
}