Mad lab

 Ex.No.1 Develop an application that uses GUI components, Font and Colors.

DATE: 

AIM:

To develop android apps that uses GUI components, Font and Colors.

PROCEDURE:

Start android visual studio application.

Create new project and select empty activity.

Add source code in activity_main.xml,strings.xml,mainactivity.java.

Include required packages and designs.

Compile the code and execute the application.

Run the application in emulators.

Stop the execution.

PROGRAM:

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/textView"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_margin="30dp"

        android:gravity="center"

        android:text="Hello World!"

        android:textSize="25sp"

        android:textStyle="bold" />

 

    <Button

        android:id="@+id/button1"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_margin="20dp"

        android:gravity="center"

        android:text="Change font size"

        android:textSize="25sp" />

    <Button

        android:id="@+id/button2"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_margin="20dp"

        android:gravity="center"

        android:text="Change color"

        android:textSize="25sp" />

</LinearLayout>

MainActivity.java:

package com.example.exno1;

import android.graphics.Color;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;

public class MainActivity extends AppCompatActivity

{    int ch=1;

float font=30;

@Override

protected void onCreate(Bundle savedInstanceState)

{  super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

final TextView t= (TextView) findViewById(R.id.textView);

Button b1= (Button) findViewById(R.id.button1);

b1.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

t.setTextSize(font);

font = font + 5;

if (font == 50)

font = 30;            }        });

Button b2= (Button) findViewById(R.id.button2);

b2.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View v) {

switch (ch) {

case 1:   t.setTextColor(Color.RED);

break;

case 2:   t.setTextColor(Color.GREEN);

break;

case 3:  t.setTextColor(Color.BLUE);

break;

case 4:   t.setTextColor(Color.CYAN);

break;

case 5:

t.setTextColor(Color.YELLOW);

break;

case 6:

t.setTextColor(Color.MAGENTA);

break;                }

ch++;

if (ch == 7)

ch = 1; }  }); }

}

Output:

RESULT:

Thus the program to develop android apps that uses GUI components, Font and Colors was executed sucessfully.

EX.NO.2 Develop an application that uses Layout Managers and event listeners.

DATE:

AIM:

To develop android apps that uses Layout Managers and event listeners.

EVENT LISTENERS:

Events are a useful way to collect data about a user's interaction with interactive components of Applications. Like button presses or screen touch etc. The Android framework maintains an event queue as first-in, first-out (FIFO) basis. You can capture these events in your program and take appropriate action as per requirements.

There are following three concepts related to Android Event Management −

Event Listeners − An event listener is an interface in the View class that contains a single callback method. These methods will be called by the Android framework when the View to which the listener has been registered is triggered by user interaction with the item in the UI.

Event Listeners Registration − Event Registration is the process by which an Event Handler gets registered with an Event Listener so that the handler is called when the Event Listener fires the event.

Event Handlers − When an event happens and we have registered an event listener for the event, the event listener calls the Event Handlers, which is the method that actually handles the event.

MainActivity.java:

package com.example.ex2;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import android.content.Intent;

//import android.support.v7.app.AppCompatActivity;

//import android.os.Bundle;

import android.view.View;

import android.widget.ArrayAdapter;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Spinner;

public class MainActivity extends AppCompatActivity {

    //Defining the Views

    EditText e1,e2;

    Button bt;

    Spinner s;

    //Data for populating in Spinner

    String [] dept_array={"CSE","ECE","IT","Mech","Civil"};

    String name,reg,dept;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        //Referring the Views

        e1= (EditText) findViewById(R.id.editText);

        e2= (EditText) findViewById(R.id.editText2);

        bt= (Button) findViewById(R.id.button);

        s= (Spinner) findViewById(R.id.spinner);

        //Creating Adapter for Spinner for adapting the data from array to Spinner

        ArrayAdapter adapter= new ArrayAdapter(MainActivity.this,android.R.layout.simple_spinner_item,dept_array);

        s.setAdapter(adapter);

        //Creating Listener for Button

        bt.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                //Getting the Values from Views(Edittext & Spinner)

                name=e1.getText().toString();

                reg=e2.getText().toString();

                dept=s.getSelectedItem().toString();

                //Intent For Navigating to Second Activity

                Intent i = new Intent(MainActivity.this,Main2Activity.class);

                //For Passing the Values to Second Activity

                i.putExtra("name_key", name);

                i.putExtra("reg_key",reg);

                i.putExtra("dept_key", dept);

                startActivity(i);

            }

        });

    }

}

 Activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context=".MainActivity">

    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="100dp">

        <TextView

            android:id="@+id/textView"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_margin="30dp"

            android:text="Details Form"

            android:textSize="25sp"

            android:gravity="center"/>

    </LinearLayout>

    <GridLayout

        android:id="@+id/gridLayout"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:layout_marginTop="100dp"

        android:layout_marginBottom="200dp"

        android:columnCount="2"

        android:rowCount="3">

        <TextView

            android:id="@+id/textView1"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_margin="10dp"

            android:layout_row="0"

            android:layout_column="0"

            android:text="Name"

            android:textSize="20sp"

            android:gravity="center"/>

        <EditText

            android:id="@+id/editText"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_margin="10dp"

            android:layout_row="0"

            android:layout_column="1"

            android:ems="10"/>

        <TextView

            android:id="@+id/textView2"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_margin="10dp"

            android:layout_row="1"

            android:layout_column="0"

            android:text="Reg.No"

            android:textSize="20sp"

            android:gravity="center"/>

        <EditText

            android:id="@+id/editText2"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_margin="10dp"

            android:layout_row="1"

            android:layout_column="1"

            android:inputType="number"

            android:ems="10"/>

        <TextView

            android:id="@+id/textView3"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_margin="10dp"

            android:layout_row="2"

            android:layout_column="0"

            android:text="Dept"

            android:textSize="20sp"

            android:gravity="center"/>

        <Spinner

            android:id="@+id/spinner"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_margin="10dp"

            android:layout_row="2"

            android:layout_column="1"

            android:spinnerMode="dropdown"/>

    </GridLayout>

    <Button

        android:id="@+id/button"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignParentBottom="true"

        android:layout_centerInParent="true"

        android:layout_marginBottom="150dp"

        android:text="Submit"/>

</RelativeLayout>

Activity_main2.xml:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    tools:context="com.example.newex.Main2Activity"

    android:orientation="vertical"

    android:gravity="center">

    <TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_margin="20dp"

        android:text="New Text"

        android:textSize="30sp"/>

    <TextView

        android:id="@+id/textView2"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_margin="20dp"

        android:text="New Text"

        android:textSize="30sp"/>

    <TextView

        android:id="@+id/textView3"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_margin="20dp"

        android:text="New Text"

        android:textSize="30sp"/>

</LinearLayout>

MainActivity2.java 

package com.example.ex2;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

import android.content.Intent;

//import android.support.v7.app.AppCompatActivity;

//import android.os.Bundle;

import android.widget.TextView;

public class Main2Activity extends AppCompatActivity {

    TextView t1,t2,t3;

    String name,reg,dept;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main2);

        t1= (TextView) findViewById(R.id.textView1);

        t2= (TextView) findViewById(R.id.textView2);

        t3= (TextView) findViewById(R.id.textView3);

        //Getting the Intent

        Intent i = getIntent();

        //Getting the Values from First Activity using the Intent received

        name=i.getStringExtra("name_key");

        reg=i.getStringExtra("reg_key");

        dept=i.getStringExtra("dept_key");

        //Setting the Values to Intent

        t1.setText(name);

        t2.setText(reg);

        t3.setText(dept); }}

Output:

RESULT:

Thus the program to develop android apps that uses Layout Managers and event listeners was executed successfully.

Ex.No:3 DEVELOP A NATIVE CALCULATOR APPLICATION

DATE:

AIM:

To Develop Android Apps a Native Calculator Application.

PROCEDURE:

Start android visual studio

Create new project as Calculator and select empty activity

Import the necessary packages.

Add source code in activity_main.xml,strings.xml,mainactivity.java

Create a buttons for performing basic operations such as addition, subtraction, multiplication, division.

Create  the function for these operations and added to the source code

Compile the code and execute the application

Run the application in emulators

Stop the execution

Program:

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"

    android:layout_margin="20dp">

 

    <LinearLayout

        android:id="@+id/linearLayout1"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_margin="20dp">

 

        <EditText

            android:id="@+id/editText1"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:inputType="numberDecimal"

            android:textSize="20sp" />

 

        <EditText

            android:id="@+id/editText2"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:inputType="numberDecimal"

            android:textSize="20sp" />

 

    </LinearLayout>

 

    <LinearLayout

        android:id="@+id/linearLayout2"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_margin="20dp">

 

        <Button

            android:id="@+id/Add"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="+"

            android:textSize="30sp"/>

 

        <Button

            android:id="@+id/Sub"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="-"

            android:textSize="30sp"/>

 

        <Button

            android:id="@+id/Mul"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="*"

            android:textSize="30sp"/>

 

        <Button

            android:id="@+id/Div"

            android:layout_width="match_parent"

            android:layout_height="wrap_content"

            android:layout_weight="1"

            android:text="/"

            android:textSize="30sp"/>

 

    </LinearLayout>

 

    <TextView

        android:id="@+id/textView"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_marginTop="50dp"

        android:text="Answer is"

        android:textSize="30sp"

        android:gravity="center"/>

 

</LinearLayout>

MainActivity.java:

package com.example.devang.exno3;

 

import android.os.Bundle;

//import android.support.v7.app.AppCompatActivity;

import androidx.appcompat.app.AppCompatActivity;

import android.text.TextUtils;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;

 

public class MainActivity extends AppCompatActivity implements OnClickListener

{

    //Defining the Views

    EditText Num1;

    EditText Num2;

    Button Add;

    Button Sub;

    Button Mul;

    Button Div;

    TextView Result;

 

    @Override

    public void onCreate(Bundle savedInstanceState)

    {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

 

        //Referring the Views

        Num1 = (EditText) findViewById(R.id.editText1);

        Num2 = (EditText) findViewById(R.id.editText2);

        Add = (Button) findViewById(R.id.Add);

        Sub = (Button) findViewById(R.id.Sub);

        Mul = (Button) findViewById(R.id.Mul);

        Div = (Button) findViewById(R.id.Div);

        Result = (TextView) findViewById(R.id.textView);

 

        // set a listener

        Add.setOnClickListener(this);

        Sub.setOnClickListener(this);

        Mul.setOnClickListener(this);

        Div.setOnClickListener(this);

    }

     

    @Override

    public void onClick (View v)

    {

         

        float num1 = 0;

        float num2 = 0;

        float result = 0;

        String oper = "";

 

        // check if the fields are empty

        if (TextUtils.isEmpty(Num1.getText().toString()) || TextUtils.isEmpty(Num2.getText().toString()))

                return;

 

        // read EditText and fill variables with numbers

        num1 = Float.parseFloat(Num1.getText().toString());

        num2 = Float.parseFloat(Num2.getText().toString());

 

        // defines the button that has been clicked and performs the corresponding operation

        // write operation into oper, we will use it later for output

        switch (v.getId()) 

        {

            case R.id.Add:

                oper = "+";

                result = num1 + num2;

                break;

            case R.id.Sub:

                oper = "-";

                result = num1 - num2;

                break;

            case R.id.Mul:

                oper = "*";

                result = num1 * num2;

                break;

            case R.id.Div:

                oper = "/";

                result = num1 / num2;

                break;

            default:

                break;

        }

        // form the output line

        Result.setText(num1 + " " + oper + " " + num2 + " = " + result);

    }

}

Output:

RESULT:

Thus the program to develop mobile application for calculator had been executed successfully.

Ex.No:4         Write an application that draws basic graphical primitives on the screen.

DATE:

AIM:

To Develop Android apps Write an Application That Draws Basic Graphical Primitives on the Screen.

PROCEDURE:

Start android visual studio application

Create new project and select empty activity

Add source code in activity_main.xml,strings.xml,mainactivity.java

Include required packages and designs

Compile the code and execute the application

Run the application in emulators

Stop the execution

Program:

Activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

 

    <ImageView

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:id="@+id/imageView" />

</RelativeLayout>

MainActivity.java:

package com.example.exno4;

 

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.drawable.BitmapDrawable;

import android.os.Bundle;

import android.widget.ImageView;

 

public class MainActivity extends Activity 

{

    @Override

    public void onCreate(Bundle savedInstanceState) 

    {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

 

        //Creating a Bitmap

        Bitmap bg = Bitmap.createBitmap(720, 1280, Bitmap.Config.ARGB_8888);

 

        //Setting the Bitmap as background for the ImageView

        ImageView i = (ImageView) findViewById(R.id.imageView);

        i.setBackgroundDrawable(new BitmapDrawable(bg));

 

        //Creating the Canvas Object

        Canvas canvas = new Canvas(bg);

 

        //Creating the Paint Object and set its color & TextSize

        Paint paint = new Paint();

        paint.setColor(Color.BLUE);

        paint.setTextSize(50);

 

        //To draw a Rectangle

        canvas.drawText("Rectangle", 420, 150, paint);

        canvas.drawRect(400, 200, 650, 700, paint);

 

        //To draw a Circle

        canvas.drawText("Circle", 120, 150, paint);

        canvas.drawCircle(200, 350, 150, paint);

 

        //To draw a Square

        canvas.drawText("Square", 120, 800, paint);

        canvas.drawRect(50, 850, 350, 1150, paint);

 

        //To draw a Line

        canvas.drawText("Line", 480, 800, paint);

        canvas.drawLine(520, 850, 520, 1150, paint);

    }

}

Output:

RESULT :

Thus the program to develop Android application that draws basic graphical primitives on the screen was executed successfully.

Ex.No:5                    Develop an application that makes use of database.

DATE:

AIM:

To Develop Android Apps an Application That Makes Use of Database.

PROCEDURE:

Start android visual studio application

Create new project as Database Demo and select empty activity

Add source code in activity_main.xml,strings.xml,mainactivity.java

Create a functions such as insert(), delete(), modify(),view() and included in Mainactivity.java

Include required packages and designs

Compile the code and execute the application

Run the application in emulators

Stop the execution

Program:

Activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>

<AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent">

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_x="50dp"

        android:layout_y="20dp"

        android:text="Student Details"

        android:textSize="30sp" />

 

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_x="20dp"

        android:layout_y="110dp"

        android:text="Enter Rollno:"

        android:textSize="20sp" />

 

    <EditText

        android:id="@+id/Rollno"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="175dp"

        android:layout_y="100dp"

        android:inputType="number"

        android:textSize="20sp" />

 

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_x="20dp"

        android:layout_y="160dp"

        android:text="Enter Name:"

        android:textSize="20sp" />

 

    <EditText

        android:id="@+id/Name"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="175dp"

        android:layout_y="150dp"

        android:inputType="text"

        android:textSize="20sp" />

 

    <TextView

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_x="20dp"

        android:layout_y="210dp"

        android:text="Enter Marks:"

        android:textSize="20sp" />

 

    <EditText

        android:id="@+id/Marks"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="175dp"

        android:layout_y="200dp"

        android:inputType="number"

        android:textSize="20sp" />

 

    <Button

        android:id="@+id/Insert"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="25dp"

        android:layout_y="300dp"

        android:text="Insert"

        android:textSize="30dp" />

 

    <Button

        android:id="@+id/Delete"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="200dp"

        android:layout_y="300dp"

        android:text="Delete"

        android:textSize="30dp" />

 

    <Button

        android:id="@+id/Update"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="25dp"

        android:layout_y="400dp"

        android:text="Update"

        android:textSize="30dp" />

 

    <Button

        android:id="@+id/View"

        android:layout_width="150dp"

        android:layout_height="wrap_content"

        android:layout_x="200dp"

        android:layout_y="400dp"

        android:text="View"

        android:textSize="30dp" />

 

    <Button

        android:id="@+id/ViewAll"

        android:layout_width="200dp"

        android:layout_height="wrap_content"

        android:layout_x="100dp"

        android:layout_y="500dp"

        android:text="View All"

        android:textSize="30dp" />

 

</AbsoluteLayout>

MainActivity.java:

package com.example.exno5;

 

import android.app.Activity;

import android.app.AlertDialog.Builder;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.EditText;

 

public class MainActivity extends Activity implements OnClickListener

{

    EditText Rollno,Name,Marks;

    Button Insert,Delete,Update,View,ViewAll;

    SQLiteDatabase db;

    /** Called when the activity is first created. */

    @Override

    public void onCreate(Bundle savedInstanceState)

    {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

 

        Rollno=(EditText)findViewById(R.id.Rollno);

        Name=(EditText)findViewById(R.id.Name);

        Marks=(EditText)findViewById(R.id.Marks);

        Insert=(Button)findViewById(R.id.Insert);

        Delete=(Button)findViewById(R.id.Delete);

        Update=(Button)findViewById(R.id.Update);

        View=(Button)findViewById(R.id.View);

        ViewAll=(Button)findViewById(R.id.ViewAll);

 

        Insert.setOnClickListener(this);

        Delete.setOnClickListener(this);

        Update.setOnClickListener(this);

        View.setOnClickListener(this);

        ViewAll.setOnClickListener(this);

 

        // Creating database and table

        db=openOrCreateDatabase("StudentDB", Context.MODE_PRIVATE, null);

        db.execSQL("CREATE TABLE IF NOT EXISTS student(rollno VARCHAR,name VARCHAR,marks VARCHAR);");

    }

    public void onClick(View view)

    {

        // Inserting a record to the Student table

        if(view==Insert)

        {

            // Checking for empty fields

            if(Rollno.getText().toString().trim().length()==0||

                    Name.getText().toString().trim().length()==0||

                    Marks.getText().toString().trim().length()==0)

            {

                showMessage("Error", "Please enter all values");

                return;

            }

            db.execSQL("INSERT INTO student VALUES('"+Rollno.getText()+"','"+Name.getText()+

                    "','"+Marks.getText()+"');");

            showMessage("Success", "Record added");

            clearText();

        }

        // Deleting a record from the Student table

        if(view==Delete)

        {

            // Checking for empty roll number

            if(Rollno.getText().toString().trim().length()==0)

            {

                showMessage("Error", "Please enter Rollno");

                return;

            }

            Cursor c=db.rawQuery("SELECT * FROM student WHERE rollno='"+Rollno.getText()+"'", null);

            if(c.moveToFirst())

            {

                db.execSQL("DELETE FROM student WHERE rollno='"+Rollno.getText()+"'");

                showMessage("Success", "Record Deleted");

            }

            else

            {

                showMessage("Error", "Invalid Rollno");

            }

            clearText();

        }

        // Updating a record in the Student table

        if(view==Update)

        {

            // Checking for empty roll number

            if(Rollno.getText().toString().trim().length()==0)

            {

                showMessage("Error", "Please enter Rollno");

                return;

            }

            Cursor c=db.rawQuery("SELECT * FROM student WHERE rollno='"+Rollno.getText()+"'",   null);

            if(c.moveToFirst()) {

                db.execSQL("UPDATE student SET name='" + Name.getText() + "',marks='" + Marks.getText() +

                        "' WHERE rollno='"+Rollno.getText()+"'");

                showMessage("Success", "Record Modified");

            }

            else {

                showMessage("Error", "Invalid Rollno");

            }

            clearText();

        }

        // Display a record from the Student table

        if(view==View)

        {

            // Checking for empty roll number

            if(Rollno.getText().toString().trim().length()==0)

            {

                showMessage("Error", "Please enter Rollno");

                return;

            }

            Cursor c=db.rawQuery("SELECT * FROM student WHERE rollno='"+Rollno.getText()+"'", null);

            if(c.moveToFirst())

            {

                Name.setText(c.getString(1));

                Marks.setText(c.getString(2));

            }

            else

            {

                showMessage("Error", "Invalid Rollno");

                clearText();

            }

        }

        // Displaying all the records

        if(view==ViewAll)

        {

            Cursor c=db.rawQuery("SELECT * FROM student", null);

            if(c.getCount()==0)

            {

                showMessage("Error", "No records found");

                return;

            }

            StringBuffer buffer=new StringBuffer();

            while(c.moveToNext())

            {

                buffer.append("Rollno: "+c.getString(0)+"\n");

                buffer.append("Name: "+c.getString(1)+"\n");

                buffer.append("Marks: "+c.getString(2)+"\n\n");

            }

            showMessage("Student Details", buffer.toString());

        }

    }

    public void showMessage(String title,String message)

    {

        Builder builder=new Builder(this);

        builder.setCancelable(true);

        builder.setTitle(title);

        builder.setMessage(message);

        builder.show();

    }

    public void clearText()

    {

        Rollno.setText("");

        Name.setText("");

        Marks.setText("");

        Rollno.requestFocus();

    }

}

Output:

RESULT :

Thus the program to develop a mobile application that make use of databases was executed successfully.