Android_slip_13B

1. Create Database Helper Class (DBHelper.java):

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {

private static final String DATABASE_NAME = "StudentDB";
private static final int DATABASE_VERSION = 1;

// Table and column names
private static final String TABLE_STUDENT = "Student";
private static final String COLUMN_SID = "Sid";
private static final String COLUMN_SNAME = "Sname";
private static final String COLUMN_PHNO = "phno";

// Create table query
private static final String CREATE_TABLE_STUDENT = "CREATE TABLE " + TABLE_STUDENT + " ("
+ COLUMN_SID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ COLUMN_SNAME + " TEXT, "
+ COLUMN_PHNO + " TEXT)";

public DBHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
// Create tables
db.execSQL(CREATE_TABLE_STUDENT);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop existing tables and recreate them if needed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_STUDENT);
onCreate(db);
}

// Method to add a student
public long addStudent(String name, String phoneNumber) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(COLUMN_SNAME, name);
values.put(COLUMN_PHNO, phoneNumber);

long rowId = db.insert(TABLE_STUDENT, null, values);
db.close();
return rowId;
}

// Method to get all students
public Cursor getAllStudents() {
SQLiteDatabase db = this.getReadableDatabase();
return db.rawQuery("SELECT * FROM " + TABLE_STUDENT, null);
}

// Method to delete a student
public void deleteStudent(long studentId) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_STUDENT, COLUMN_SID + "=?", new String[]{String.valueOf(studentId)});
db.close();
}
}

2. Layout (activity_main.xml):

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="16dp">

<EditText
android:id="@+id/editTextName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Enter Name"/>

<EditText
android:id="@+id/editTextPhoneNumber"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:hint="Enter Phone Number"
android:inputType="phone"/>

<Button
android:id="@+id/btnAddStudent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Add Student"/>

<Button
android:id="@+id/btnShowStudents"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Show Students"/>

<Button
android:id="@+id/btnDeleteStudent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Delete Student"/>
</LinearLayout>

3. MainActivity Class (MainActivity.java):

import android.database.Cursor;
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;

public class MainActivity extends AppCompatActivity {

private EditText editTextName, editTextPhoneNumber;
private Button btnAddStudent, btnShowStudents, btnDeleteStudent;
private DBHelper dbHelper;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

editTextName = findViewById(R.id.editTextName);
editTextPhoneNumber = findViewById(R.id.editTextPhoneNumber);
btnAddStudent = findViewById(R.id.btnAddStudent);
btnShowStudents = findViewById(R.id.btnShowStudents);
btnDeleteStudent = findViewById(R.id.btnDeleteStudent);

dbHelper = new DBHelper(this);

btnAddStudent.setOnClickListener(new View.OnClickListener() {
@Override
public void o-nClick(View v) {
addStudent();
}
});

btnShowStudents.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
showStudents();
}
});

btnDeleteStudent.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
deleteStudent();
}
});
}

private void addStudent() {
String name = editTextName.getText().toString().trim();
String phoneNumber = editTextPhoneNumber.getText().toString().trim();

if (!name.isEmpty() && !phoneNumber.isEmpty()) {
long rowId = dbHelper.addStudent(name, phoneNumber);

if (rowId != -1) {
Toast.makeText(this, "Student added successfully!", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "Error adding student", Toast.LENGTH_SHORT).show();
}
} else {
Toast.makeText(this, "Please enter name and phone number", Toast.LENGTH_SHORT).show();
}
}

private void showStudents() {
Cursor cursor = dbHelper.getAllStudents();

StringBuilder studentsInfo = new StringBuilder("Students:\n");
while (cursor.moveToNext()) {
int sid = cursor.getInt(cursor.getColumnIndex(DBHelper.COLUMN_SID));
String name = cursor.getString(cursor.getColumnIndex(DBHelper.COLUMN_SNAME));
String phoneNumber = cursor.getString(cursor.getColumnIndex(DBHelper.COLUMN_PHNO));

studentsInfo.append("ID: ").append(sid).append(", Name: ").append(name)
.append(", Phone Number: ").append(phoneNumber).append("\n");
}

if (studentsInfo.length() > 0) {
Toast.makeText(this, studentsInfo.toString(), Toast.LENGTH_LONG).show();
} else {
Toast.makeText(this, "No students found", Toast.LENGTH_SHORT).show();
}
}

private void deleteStudent() {
// For simplicity, this example deletes the first student. In a real app, you might want to select the student to delete.
Cursor cursor = dbHelper.getAllStudents();
if (cursor.moveToFirst()) {
long studentId = cursor.getLong(cursor.getColumnIndex(DBHelper.COLUMN_SID));
dbHelper.deleteStudent(studentId);
Toast.makeText(this, "Student deleted successfully!", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(this, "No students to delete", Toast.LENGTH_SHORT).show();
}
}
}