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Android Kotlin Checkbox example

MainActivity.kt

package com.example.checkboxdemo

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
// author : www.raviroza.com
// date : 2-Jan-2023, 9.00 am
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity()
{
    var ch = mutableSetOf("")
    fun setChoices()
    {
        var t = ""
        for(tt in ch)
        {
            t = t + tt + " "
        }
        lblChoiceList.text = t.toString()
    }

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

        /*chkCricket.setOnClickListener()
        {
            if(chkCricket.isChecked == true)
            {
                ch.add(chkCricket.text.toString())
            }
            else
            {
                ch.remove(chkCricket.text.toString())
            }
            lblChoiceList.text = ch.toString()
        }
        chkFootBall.setOnClickListener()
        {
            if(chkFootBall.isChecked == true)
            {
                ch.add(chkFootBall.text.toString())
            }
            else
            {
                ch.remove(chkFootBall.text.toString())
            }
            lblChoiceList.text = ch.toString()
        }
        chkKabbadi.setOnClickListener()
        {
            if(chkKabbadi.isChecked == true)
            {
                ch.add(chkKabbadi.text.toString())
            }
            else
            {
                ch.remove(chkKabbadi.text.toString())
            }
            lblChoiceList.text = ch.toString()
        }

        chkFootBall.setOnClickListener()
        {
            lblChoiceList.text = lblChoiceList.text.toString() + chkFootBall.text.toString()
        }
        chkKabbadi.setOnClickListener()
        {
            lblChoiceList.text = lblChoiceList.text.toString() + chkKabbadi.text.toString()
        }*/


       chkCricket.setOnCheckedChangeListener { buttonView, isChecked ->
            if (isChecked)
            {
                ch.add(buttonView.text.toString())
                setChoices()
            }
            else
            {
                ch.remove(buttonView.text.toString())
                setChoices()
            }
        }
        chkFootBall.setOnCheckedChangeListener { buttonView, isChecked ->
            if (isChecked)
            {
                ch.add(buttonView.text.toString())
                setChoices()
            }
            else
            {
                ch.remove(buttonView.text.toString())
                setChoices()
            }
        }
        chkKabbadi.setOnCheckedChangeListener { buttonView, isChecked ->
            if (isChecked)
            {
                ch.add(buttonView.text.toString())
                setChoices()
            }
            else
            {
                ch.remove(buttonView.text.toString())
                setChoices()
            }
        }
    }
}

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:layout_margin="4dp"
android:background="@color/MainColor"
    tools:context=".MainActivity" >

    <LinearLayout
        android:background="@color/SubColor"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginStart="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginBottom="8dp"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:id="@+id/lblHead"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="4dp"
            android:background="#2196F3"
            android:gravity="center"
            android:text="Check Box Demo"
            android:textColor="#232031"
            android:textSize="30sp" />

        <TextView
            android:id="@+id/lblSubHead"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="4dp"
            android:gravity="center"
            android:text="Select Your Game"
            android:textSize="18sp" />

        <CheckBox
            android:id="@+id/chkCricket"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="4dp"
            android:text="@string/cricket"
            android:textSize="18sp" />

        <CheckBox
            android:id="@+id/chkKabbadi"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="4dp"
            android:text="@string/Kabbadi"
            android:textSize="18sp" />

        <CheckBox
            android:id="@+id/chkFootBall"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="4dp"
            android:text="@string/Football"
            android:textSize="18sp" />

        <TextView
            android:id="@+id/lblHereAreYourChoices"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="4dp"
            android:gravity="center"
            android:background="#4876a8"
            android:text="Your Choices are "
            android:textSize="18sp" />

        <TextView
            android:id="@+id/lblChoiceList"
            android:layout_width="match_parent"
            android:layout_height="301dp"
            android:layout_margin="4dp"
            android:gravity="center_horizontal"
            android:text=".... "
            android:textSize="18sp" />

    </LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

Android Kotlin SQLite Demo

Here is the example of Android with Kotlin SQLite database in Android Studio.

MainActivity.kt

package com.example.sqlitedemo

import android.content.Context

// Author : www.raviroza.com
// Date : 26-Dec-2022, 10.00 am

import android.database.Cursor
import android.database.sqlite.SQLiteDatabase
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    lateinit var DB : SQLiteDatabase
    lateinit var QRY : String
    lateinit var CURSOR : Cursor

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

        DB = openOrCreateDatabase("MyDB", Context.MODE_PRIVATE,null)

        Toast.makeText(this,DB.path.toString(),Toast.LENGTH_LONG).show()

        QRY = "CREATE TABLE IF NOT EXISTS student(rollno VARCHAR,name VARCHAR,marks VARCHAR);"

        DB.execSQL(QRY)

        Toast.makeText(this,"Table Created !",Toast.LENGTH_LONG).show()
        loadData()

        btnAdd.setOnClickListener()
        {
            QRY = "insert into student values ( ${txtRollNo.text} , '${txtName.text}' , ${txtMarks.text} )"
            DB.execSQL(QRY)
            Toast.makeText(this,"Record Inserted !",Toast.LENGTH_LONG).show()
            txtName.text = null
            txtMarks.text = null
            txtRollNo.text = null
            loadData()

        }

    }
    fun loadData()
    {
        QRY = "Select * from Student "
        CURSOR = DB.rawQuery(QRY,null)
        var data : String = ""
        while (CURSOR.moveToNext())
        {
            data += CURSOR.getString(0) + "\n"
            data += CURSOR.getString(1) + "\n"
            data += "-------------------------------\n"
        }
        if(data.length==0) {

            lblResult.text = "No Records Found"
        }
        else
        {
            lblResult.text = data
        }
    }
}

activity_main.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:layout_margin="16dp"
    tools:context=".MainActivity">

<!--    Author : www.raviroza.com-->
<!--    Date : 26-Dec-2022, 10.00 am-->

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="DB App Demo - Student"
        android:textSize="25dp"
        android:gravity="center"
        android:background="@color/colorAccent"
        android:padding="8dp"
         />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Enter Roll No. :"
        android:textSize="20dp"
        />

    <EditText
        android:id="@+id/txtRollNo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="0"
        android:inputType="number"
        android:textSize="20dp"

        />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Enter Name :"
        android:textSize="20dp"
        />

    <EditText
        android:id="@+id/txtName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Enter Marks:"
        android:textSize="20dp"
        />

    <EditText
        android:id="@+id/txtMarks"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="20dp"
        android:inputType="number"
        />

    <Button
        android:id="@+id/btnAdd"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="25dp"
        android:text="Add Record"
        android:textAllCaps="false"
        />
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    <TextView
        android:id="@+id/lblResult"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="4dp"
        android:text="student data"
        android:textSize="18dp"
        />

    </ScrollView>

</LinearLayout>
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