Sqlite Example in Kotlin

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/fstTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="100dp"
        android:layout_marginTop="150dp"
        android:text="Name" />
    <EditText
        android:id="@+id/txtName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="100dp"
        android:ems="10"/>
    <TextView
        android:id="@+id/secTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Location"
        android:layout_marginLeft="100dp" />
    <EditText
        android:id="@+id/txtLocation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="100dp"
        android:ems="10" />
    <TextView
        android:id="@+id/thirdTxt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Designation"
        android:layout_marginLeft="100dp" />
    <EditText
        android:id="@+id/txtDesignation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="100dp"
        android:ems="10" />
    <Button
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="100dp"
        android:text="Save" />
</LinearLayout>

MainActivity.kt

package com.androindian.sqlite

import android.content.Intent
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {
    var name: EditText? = null
    var loc: EditText? = null
    var desig: EditText? = null
    var saveBtn: Button? = null
    var intent: Intent? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        name = findViewById(R.id.txtName)
        loc = findViewById(R.id.txtLocation)
        desig = findViewById(R.id.txtDesignation)
        saveBtn = findViewById(R.id.btnSave)
        saveBtn?.setOnClickListener(View.OnClickListener {
            val username = """
                ${name?.getText()}
                
                """.trimIndent()
            val location = loc?.getText().toString()
            val designation = desig?.getText().toString()
            val dbHandler = DbHandler(this@MainActivity)
            dbHandler.insertUserDetails(username, location, designation)
            intent = Intent(this@MainActivity, DetailsActivity::class.java)
            startActivity(intent)
            Toast.makeText(applicationContext, "Details Inserted Successfully", Toast.LENGTH_SHORT)
                .show()
        })
    }
}

Dbhelper.kt

package com.androindian.sqlite

import android.annotation.SuppressLint
import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper

class DbHandler(context: Context?) : SQLiteOpenHelper(context, DB_NAME, null, DB_VERSION) {
    override fun onCreate(db: SQLiteDatabase) {
        val CREATE_TABLE = ("CREATE TABLE " + TABLE_Users + "("
                + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + KEY_NAME + " TEXT,"
                + KEY_LOC + " TEXT,"
                + KEY_DESG + " TEXT" + ")")
        db.execSQL(CREATE_TABLE)
    }

    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        // Drop older table if exist
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_Users)
        // Create tables again
        onCreate(db)
    }

    // **** CRUD (Create, Read, Update, Delete) Operations ***** //
    // Adding new User Details
    fun insertUserDetails(name: String?, location: String?, designation: String?) {
        //Get the Data Repository in write mode
        val db = this.writableDatabase
        //Create a new map of values, where column names are the keys
        val cValues = ContentValues()
        cValues.put(KEY_NAME, name)
        cValues.put(KEY_LOC, location)
        cValues.put(KEY_DESG, designation)
        // Insert the new row, returning the primary key value of the new row
        val newRowId = db.insert(TABLE_Users, null, cValues)
        db.close()
    }

    // Get User Details
    @SuppressLint("Range")
    fun GetUsers(): ArrayList<HashMap<String, String>> {
        val db = this.writableDatabase
        val userList = ArrayList<HashMap<String, String>>()
        val query = "SELECT name, location, designation FROM " + TABLE_Users
        val cursor = db.rawQuery(query, null)
        while (cursor.moveToNext()) {
            val user = HashMap<String, String>()
            user["name"] = cursor.getString(cursor.getColumnIndex(KEY_NAME))
            user["designation"] = cursor.getString(cursor.getColumnIndex(KEY_DESG))
            user["location"] = cursor.getString(cursor.getColumnIndex(KEY_LOC))
            userList.add(user)
        }
        return userList
    }

    // Get User Details based on userid
    @SuppressLint("Range")
    fun GetUserByUserId(userid: Int): ArrayList<HashMap<String, String>> {
        val db = this.writableDatabase
        val userList = ArrayList<HashMap<String, String>>()
        val query = "SELECT name, location, designation FROM " + TABLE_Users
        val cursor = db.query(
            TABLE_Users,
            arrayOf(KEY_NAME, KEY_LOC, KEY_DESG),
            KEY_ID + "=?",
            arrayOf(userid.toString()),
            null,
            null,
            null,
            null
        )
        if (cursor.moveToNext()) {
            val user = HashMap<String, String>()
            user["name"] = cursor.getString(cursor.getColumnIndex(KEY_NAME))
            user["designation"] = cursor.getString(cursor.getColumnIndex(KEY_DESG))
            user["location"] = cursor.getString(cursor.getColumnIndex(KEY_LOC))
            userList.add(user)
        }
        return userList
    }

    // Delete User Details
    fun DeleteUser(userid: Int) {
        val db = this.writableDatabase
        db.delete(TABLE_Users, KEY_ID + " = ?", arrayOf(userid.toString()))
        db.close()
    }

    // Update User Details
    fun UpdateUserDetails(
        location: String?,
        designation: String?,
        id: Int
    ): Int {
        val db = this.writableDatabase
        val cVals = ContentValues()
        cVals.put(KEY_LOC, location)
        cVals.put(KEY_DESG, designation)
        return db.update(TABLE_Users, cVals, "$KEY_ID = ?", arrayOf(id.toString()))
    }

    companion object {
        private const val DB_VERSION = 1
        private const val DB_NAME = "usersdb"
        private const val TABLE_Users = "userdetails"
        private const val KEY_ID = "id"
        private const val KEY_NAME = "name"
        private const val KEY_LOC = "location"
        private const val KEY_DESG = "designation"
    }
}

activity_data.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=".Data">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="data"
        android:textSize="18sp"
        android:textStyle="bold" />
</LinearLayout>

DeatilsActivity.kt

package com.androindian.sqlite

import android.content.Intent
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.ListAdapter
import android.widget.ListView
import android.widget.SimpleAdapter
import androidx.appcompat.app.AppCompatActivity

class DetailsActivity : AppCompatActivity() {
    var intent: Intent? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_details)
        val db = DbHandler(this)
        val userList = db.GetUsers()
        val lv = findViewById<View>(R.id.user_list) as ListView
        val adapter: ListAdapter = SimpleAdapter(
            this@DetailsActivity,
            userList,
            R.layout.list_row,
            arrayOf("name", "designation", "location"),
            intArrayOf(R.id.name, R.id.designation, R.id.location)
        )
        lv.adapter = adapter
        val back = findViewById<View>(R.id.btnBack) as Button
        back.setOnClickListener {
            intent = Intent(this@DetailsActivity, MainActivity::class.java)
            startActivity(intent)
        }
    }
}

list_row.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="5dip" >
    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textStyle="bold"
        android:textSize="17dp" />
    <TextView
        android:id="@+id/designation"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/name"
        android:layout_marginTop="7dp"
        android:textColor="#343434"
        android:textSize="14dp" />
    <TextView
        android:id="@+id/location"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/designation"
        android:layout_alignBottom="@+id/designation"
        android:layout_alignParentRight="true"
        android:textColor="#343434"
        android:textSize="14dp" />
</RelativeLayout>