Simple Android Application that makes use of Database

Aim:

To develop a Simple Android Application that makes use of Database.

Procedure:

Creating a New project:

Open Android Studio and then click on File -> New -> New project.

Then type the Application name as “ex.no.5″ and click Next.

Then select the Minimum SDK as shown below and click Next.

Then select the Empty Activity and click Next.

Finally click Finish.

It will take some time to build and load the project.
After completion it will look as given below.

Designing layout for the Android Application:

Click on app -> res -> layout -> activity_main.xml.

Now click on Text as shown below.

Then delete the code which is there and type the code as given below.

Code for 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>

Now click on Design and your application will look as given below.

So now the designing part is completed.

Java Coding for the Android Application:

Click on app -> java -> com.example.exno5 -> MainActivity.

Then delete the code which is there and type the code as given below.

Code for 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)+"nn"); } 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(); }
}