UserManagementdb

UserManagementdb.kt

MainActivity.kt:

package com.iliyadev.usermanagement

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.Button
import android.widget.EditText
import android.widget.ListView
import android.widget.Toast
import android.widget.Toast.LENGTH_LONG
import android.widget.Toast.LENGTH_SHORT
import com.iliyadev.usermanagement.db.DBContract
import com.iliyadev.usermanagement.db.helper.UserDBHelper
import com.iliyadev.usermanagement.models.User

class MainActivity : AppCompatActivity() {

    private lateinit var username: EditText
    private lateinit var firstname: EditText
    private lateinit var lastname: EditText
    private lateinit var btnAdd: Button
    private lateinit var btnDelete: Button
    private lateinit var listView: ListView
    private lateinit var userdbHelper: UserDBHelper
    private lateinit var adapter: ArrayAdapter<String>
    private var listItem = ArrayList<String>()
    private var selectedUserIndex: Int = -1

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        init()
    }

    private fun init() {
        bindViews()
        userdbHelper = UserDBHelper(this)
        refreshList()
        adapter = ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, listItem)
        listView.adapter = adapter
        btnAdd.setOnClickListener {
            if (username.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Your UserName", Toast.LENGTH_SHORT).show()
                return@setOnClickListener
            }
            if (firstname.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Your firstName", Toast.LENGTH_SHORT).show()
                return@setOnClickListener
            }
            if (lastname.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Your lastName", Toast.LENGTH_SHORT).show()
                return@setOnClickListener
            }

            val user = User(username.text.toString(), firstname.text.toString(), lastname.text.toString())
            val result = userdbHelper.insertUser(user)
            if (result) {
                Toast.makeText(this, "New User Added Successfully", Toast.LENGTH_SHORT).show()
                username.text.clear()
                firstname.text.clear()
                lastname.text.clear()
                refreshList()
                adapter.notifyDataSetChanged()
            }
        }

        listView.setOnItemClickListener { _, view, position, _ ->
            // Clear previous selection
            clearSelection()

            // Set the selected position and update the UI
            selectedUserIndex = position
            view.setBackgroundColor(resources.getColor(android.R.color.darker_gray))
        }

        btnDelete.setOnClickListener {
            if (selectedUserIndex != -1) {
                val selectedUser = adapter.getItem(selectedUserIndex)
                val userName = selectedUser!!.substringAfterLast("(").substringBefore(")")
                val result = userdbHelper.deleteUser(userName)
                if (result) {
                    Toast.makeText(this, "User deleted successfully", Toast.LENGTH_SHORT).show()
                    clearSelection()
                    refreshList()
                    adapter.notifyDataSetChanged()
                } else {
                    Toast.makeText(this, "Failed to delete user", Toast.LENGTH_SHORT).show()
                }
            } else {
                Toast.makeText(this, "Please select a user to delete", Toast.LENGTH_SHORT).show()
            }
        }
    }

    private fun clearSelection() {
        if (selectedUserIndex != -1) {
            val selectedView = listView.getChildAt(selectedUserIndex)
            selectedView?.setBackgroundColor(0)
            selectedUserIndex = -1
        }
    }

    private fun refreshList() {
        listItem.clear()
        val users = userdbHelper.getAllUsers()
        for (user in users) {
            listItem.add("${user.firstName} ${user.lastName} (${user.userName})")
        }
    }

    private fun bindViews() {
        username = findViewById(R.id.edittext_username)
        firstname = findViewById(R.id.edittext_firstname)
        lastname = findViewById(R.id.edittext_lastname)
        btnAdd = findViewById(R.id.button_adduser)
        btnDelete = findViewById(R.id.button_deleteuser)
        listView = findViewById(R.id.listView)
    }
}

User.kt:

package com.iliyadev.usermanagement.models

data class User(val userName: String, val firstName: String, val lastName: String)

DBContract object:

package com.iliyadev.usermanagement.db

import android.provider.BaseColumns

object DBContract {

    class UserEntity : BaseColumns {
        companion object {
            var TABLE_NAME = "users"
            var COLUMN_USERNAME = "username"
            var COLUMN_FIRSTNAME = "firstname"
            var COLUMN_LASTNAME = "lastname"
        }
    }
}

UserDBHelper class
package com.iliyadev.usermanagement.db.helper

import android.annotation.SuppressLint
import android.content.ContentValues
import android.content.Context
import android.database.Cursor
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
import android.widget.Toast
import com.iliyadev.usermanagement.db.DBContract
import com.iliyadev.usermanagement.models.User
import java.lang.Exception

class UserDBHelper(contex: Context) :
    SQLiteOpenHelper(contex, DATABASE_NAME, null, DATABASE_VERSION) {
    override fun onCreate(db: SQLiteDatabase?) {
        db?.execSQL(SQL_CREATE_QUERY)
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
        db?.execSQL(SQL_DELETE_QUERY)
        onCreate(db)
    }

    fun insertUser(user: User): Boolean {
        try {
            val db = writableDatabase
            val values = ContentValues()
            values.put(DBContract.UserEntity.COLUMN_USERNAME, user.userName)
            values.put(DBContract.UserEntity.COLUMN_FIRSTNAME, user.firstName)
            values.put(DBContract.UserEntity.COLUMN_LASTNAME, user.lastName)
            db.insert(DBContract.UserEntity.TABLE_NAME, null, values)
            return true
        } catch (e: Exception) {
            return false
        }
    }

    @SuppressLint("Recycle", "Range")
    fun getAllUsers(): ArrayList<User> {
        var users = ArrayList<User>()
        var db = readableDatabase
        var cursor: Cursor? = null
        try {
            cursor = db.rawQuery("SELECT * FROM ${DBContract.UserEntity.TABLE_NAME}", null)
        } catch (e: Exception) {
            db.execSQL(SQL_CREATE_QUERY)
            return ArrayList()
        }
        var username: String
        var firstName: String
        var lastName: String

        if (cursor.moveToFirst()) {
            while (!cursor.isAfterLast) {
                username =
                    cursor.getString(cursor.getColumnIndex(DBContract.UserEntity.COLUMN_USERNAME))
                firstName =
                    cursor.getString(cursor.getColumnIndex(DBContract.UserEntity.COLUMN_FIRSTNAME))
                lastName =
                    cursor.getString(cursor.getColumnIndex(DBContract.UserEntity.COLUMN_LASTNAME))
                users.add(User(username, firstName, lastName))
                cursor.moveToNext()
            }
        }
        return users
    }

    companion object {
        const val DATABASE_VERSION = 1
        const val DATABASE_NAME = "UserManagement.db"

        private var SQL_CREATE_QUERY = "CREATE TABLE ${DBContract.UserEntity.TABLE_NAME} " +
                "(${DBContract.UserEntity.COLUMN_USERNAME} TEXT PRIMARY KEY," +
                "${DBContract.UserEntity.COLUMN_FIRSTNAME} TEXT," +
                "${DBContract.UserEntity.COLUMN_LASTNAME} TEXT )"

        private var SQL_DELETE_QUERY = "DROP TABLE IF EXISTS ${DBContract.UserEntity.TABLE_NAME}"
    }

    fun deleteUser(userName: String): Boolean {
        val db = writableDatabase
        val selection = "${DBContract.UserEntity.COLUMN_USERNAME} = ?"
        val selectionArgs = arrayOf(userName)
        val deletedRows = db.delete(DBContract.UserEntity.TABLE_NAME, selection, selectionArgs)
        db.close()
        return deletedRows > 0
    }

}
    
    activity_main.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"
    android:padding="20dp"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:fontFamily="@font/advent_pro_bold"
        android:text="@string/user_management"
        android:textSize="30sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.023" />

    <EditText
        android:id="@+id/edittext_username"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="@string/username"
        android:importantForAutofill="no"
        android:inputType="text"
        android:minHeight="48dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.507"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2"
        app:layout_constraintVertical_bias="0.056"
        tools:ignore="LabelFor,VisualLintTextFieldSize" />

    <EditText
        android:id="@+id/edittext_firstname"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="@string/firstname"
        android:importantForAutofill="no"
        android:inputType="text"
        android:minHeight="48dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.6"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2"
        app:layout_constraintVertical_bias="0.176"
        tools:ignore="LabelFor,VisualLintTextFieldSize" />

    <EditText
        android:id="@+id/edittext_lastname"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="@string/lastname"
        android:importantForAutofill="no"
        android:inputType="text"
        android:minHeight="48dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView2"
        app:layout_constraintVertical_bias="0.302"
        tools:ignore="LabelFor,VisualLintTextFieldSize" />

    <Button
       
        android:id="@+id/button_adduser"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Add User"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

    <Button
        android:id="@+id/button_deleteuser"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Delete User"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

    <ListView
        android:id="@+id/listView"
        android:layout_width="363dp"
        android:layout_height="296dp"
        android:layout_marginTop="28dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/edittext_lastname"
        app:layout_constraintVertical_bias="0.009" />

</androidx.constraintlayout.widget.ConstraintLayout>