android Archives - Ravi R. Oza

Android Model Paper

November 4, 2023March 25, 2023 by Ravi Oza

BCA Sem. 6 – CS-31 | Android with Kotlin (July-2022)

Android Model Paper

November 4, 2023March 19, 2023 by Ravi Oza

BCA Sem. 6 – CS-31 | Android with Kotlin (March-2022)

Important Links for Java and Android

November 5, 2023February 10, 2023 by Ravi Oza

Java and Android Programming Tutorials

Java Hibernate Tutorials

Are Dumb phones the Smarter Choice?

November 5, 2023February 10, 2023 by Ravi Oza

Dumb phones are making a comeback. The year 2000 is calling and this time GenZ is picking up. What are these dumb phones? Why are they seeing a revival?

Android Kotlin Checkbox example

October 29, 2023January 2, 2023 by Ravi Oza

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

October 29, 2023December 26, 2022 by Ravi Oza

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>

Getters and Setter in Kotlin

October 31, 2023February 2, 2022 by Ravi Oza

Getters and Setters is also known as custom property accessors.

Kotlin Classes and Objects – Ravi R. Oza (raviroza.com)

Kotlin Assignment – 1

October 31, 2023January 29, 2022 by Ravi Oza

Kotlin Assignment – Ravi R. Oza (raviroza.com)

Android Model Paper

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Android Model Paper

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Important Links for Java and Android

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Are Dumb phones the Smarter Choice?

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Android Kotlin Checkbox example

MainActivity.kt

activity_main.xml

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Android Kotlin SQLite Demo

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Getters and Setter in Kotlin

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Kotlin Assignment – 1

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MainActivity.kt

activity_main.xml

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