UserManagement Database

usermanagementdatabase

activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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="30dp"
    tools:context=".MainActivity">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/userManagement"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:fontFamily="casual"
            android:text="@string/usermanagement"
            android:textSize="25sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <EditText
            android:id="@+id/usernametxt"
            android:layout_width="358dp"
            android:layout_height="46dp"
            android:layout_marginBottom="20dp"
            android:autofillHints=""
            android:ems="10"
            android:hint="@string/username"
            android:inputType="text"
            app:layout_constraintBottom_toTopOf="@+id/firstnametxt"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            tools:ignore="VisualLintTextFieldSize" />

        <EditText
            android:id="@+id/firstnametxt"
            android:layout_width="352dp"
            android:layout_height="41dp"
            android:layout_marginBottom="20dp"
            android:autofillHints=""
            android:ems="10"
            android:hint="@string/firsname"
            android:inputType="text"
            app:layout_constraintBottom_toTopOf="@+id/lastnametxt"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.272"
            app:layout_constraintStart_toStartOf="parent"
            tools:ignore="VisualLintTextFieldSize" />

        <EditText
            android:id="@+id/lastnametxt"
            android:layout_width="348dp"
            android:layout_height="41dp"
            android:layout_marginTop="164dp"
            android:autofillHints=""
            android:ems="10"
            android:hint="@string/lastname"
            android:inputType="text"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/userManagement"
            tools:ignore="VisualLintTextFieldSize" />

        <soup.neumorphism.NeumorphButton
            android:id="@+id/btnadduser"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginEnd="32dp"
            android:layout_marginBottom="296dp"
            android:contentDescription="@string/app_name"
            android:padding="28dp"
            android:src="@drawable/baseline_add_24"
            android:text="@string/add_user"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:neumorph_backgroundColor="@color/background"
            app:neumorph_shadowColorDark="@color/dark_shadow"
            app:neumorph_shadowColorLight="@color/light_shadow"
            app:neumorph_shadowElevation="5dp" />

        <soup.neumorphism.NeumorphButton
            android:id="@+id/btndeleteuser"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginEnd="16dp"
            android:layout_marginBottom="196dp"
            android:contentDescription="@string/app_name"
            android:padding="28dp"
            android:src="@drawable/baseline_add_24"
            android:text="@string/delete_user"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toEndOf="@+id/listview"
            app:layout_constraintTop_toBottomOf="@+id/btnadduser"
            app:neumorph_backgroundColor="@color/background"
            app:neumorph_shadowColorDark="@color/dark_shadow"
            app:neumorph_shadowColorLight="@color/light_shadow"
            app:neumorph_shadowElevation="5dp" />


        <ListView
            android:id="@+id/listview"
            android:layout_width="179dp"
            android:layout_height="410dp"
            android:layout_marginTop="16dp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.023"
            app:layout_constraintStart_toStartOf="parent"
            android:tooltipText="fdfsf"
            app:layout_constraintTop_toBottomOf="@+id/lastnametxt" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
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MainActivity.kt:

package com.example.sql

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 soup.neumorphism.NeumorphFloatingActionButton

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 allUsers = ArrayList<user>()
    private var listItems = ArrayList<String>()
    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, listItems)
        listView.adapter = adapter
        btnAdd.setOnClickListener {
            if (username.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Username", Toast.LENGTH_SHORT).show()
            }
            if (firstName.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Username", Toast.LENGTH_SHORT).show()
            }
            if (lastName.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Username", Toast.LENGTH_SHORT).show()
            }
            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 { parent, view, position, id ->
            val item = allUsers[position]
            username.setText(item.userName)
            firstName.setText(item.firstName)
            lastName.setText(item.lastName)
        }
        btnDelete.setOnClickListener{
            if (username.text.isEmpty()) {
                Toast.makeText(this, "Please Enter Username", Toast.LENGTH_SHORT).show()
            }
            val result = userDBHelper.deleteuserbyusername(username.text.toString())
            if (result) {
                Toast.makeText(this, "User deleted Successfully", Toast.LENGTH_SHORT).show()
                username.text.clear()
                firstName.text.clear()
                lastName.text.clear()
                refreshList()
                adapter.notifyDataSetChanged()
            }else{
                Toast.makeText(this, "User Not Found!", Toast.LENGTH_SHORT).show()
            }
        }
    }

    private fun refreshList() {
        allUsers.clear()
        allUsers.addAll(userDBHelper.getAllUsers())
        listItems.clear()
        listItems.addAll(
            allUsers.map { x -> "${x.firstName} ${x.lastName} (${x.userName})" } as ArrayList<String>
        )
    }

    private fun bindViews() {
        username = findViewById(R.id.usernametxt)
        firstName = findViewById(R.id.firstnametxt)
        lastName = findViewById(R.id.lastnametxt)
        btnAdd = findViewById(R.id.btnadduser)
        btnDelete = findViewById(R.id.btndeleteuser)
        listView = findViewById(R.id.listview)
    }
}

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user.kt:
package com.example.sql

data class user(val userName:String,val firstName:String,val lastName:String)
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dbcontract.object:

package com.example.sql

import android.provider.BaseColumns

object DBContract {
    class userEntity :BaseColumns{
        companion object{
            val TABLE_NAME = "users"
            val COLUMN_USERNAME = "username"
            val COLUMN_FIRSNAME = "firstname"
            val COLUMN_LASTNAME = "lastname"
        }
    }
}

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UserDBHelper.kt:

package com.example.sql

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 androidx.appcompat.app.AlertDialog
import java.lang.Exception
import soup.neumorphism.NeumorphFloatingActionButton

class UserDBHelper(context: Context) :
    SQLiteOpenHelper(context, 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 {
        return try {
            val db = writableDatabase
            val valuse = ContentValues()
            valuse.put(DBContract.userEntity.COLUMN_USERNAME, user.userName)
            valuse.put(DBContract.userEntity.COLUMN_FIRSNAME, user.firstName)
            valuse.put(DBContract.userEntity.COLUMN_LASTNAME, user.lastName)
            db.insert(DBContract.userEntity.TABLE_NAME, null, valuse)
            true
        } catch (e: Exception) {
            false
        }
    }

    @SuppressLint("Range")
    fun getAllUsers(): ArrayList<user> {
        val users = ArrayList<user>()
        val 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_FIRSNAME))
                lastname =
                    cursor.getString(cursor.getColumnIndex(DBContract.userEntity.COLUMN_LASTNAME))
                users.add(user(username, firstname, lastname))
                cursor.moveToNext()
            }
        }
        return users
    }

    @SuppressLint("Range")
    fun getUserByUsername(username: String): user? {
        val db = readableDatabase
        var cursor: Cursor? = null
        try {
            cursor = db.rawQuery(
                "SELECT * FROM ${DBContract.userEntity.TABLE_NAME} where ${DBContract.userEntity.COLUMN_USERNAME} = ?",
                arrayOf(username)
            )

        } catch (e: Exception) {
            db.execSQL(SQL_CREATE_QUERY)
            return null
        }
        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_FIRSNAME))
                lastname =
                    cursor.getString(cursor.getColumnIndex(DBContract.userEntity.COLUMN_LASTNAME))
                cursor.moveToNext()
            }
        } else {
            return null
        }
        return user(username, firstname, lastname)
    }

    fun deleteuserbyusername(username: String): Boolean {
        return try {
            val user = getUserByUsername(username) ?: throw Exception("User Not Found!")
            val db = writableDatabase
            val where = "${DBContract.userEntity.COLUMN_USERNAME} = ?"
            val args = arrayOf(username)
            db.delete(DBContract.userEntity.TABLE_NAME, where, args)
            true
        } catch (e: Exception) {
            false
        }
    }

    companion object {
        const val database_version = 1
        const val database_name = "usermanagement.db"
        private val SQL_CREATE_QUERY = "CREATE TABLE ${DBContract.userEntity.TABLE_NAME}" +
                " (${DBContract.userEntity.COLUMN_USERNAME} TEXT PRIMARY KEY," +
                " ${DBContract.userEntity.COLUMN_FIRSNAME} TEXT ," +
                " ${DBContract.userEntity.COLUMN_LASTNAME} TEXT )"
        private val SQL_DELETE_QUERY = "DROP TABLE IF EXISTS ${DBContract.userEntity.TABLE_NAME}"
    }

}

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