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Userlogin.java

+package com.example.fund_restart;
+
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.cardview.widget.CardView;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.os.Bundle;
+import android.view.View;
+import android.widget.Button;
+import android.widget.EditText;
+import android.widget.TextView;
+import android.widget.Toast;
+
+public class Userlogin extends AppCompatActivity implements View.OnClickListener {
+    EditText register_name1, register_email1, register_password1;
+    CardView btnAdd2, btnViewshow;
+    SQLiteDatabase db;
+    Button delete_data,data_search;
+    String regex = "^[\\w-_\\.+]*[\\w-_\\.]\\@([\\w]+\\.)+[\\w]+[\\w]$";
+
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_userlogin);
+        register_name1 = (EditText) findViewById(R.id.register_name1);
+        register_email1 = (EditText) findViewById(R.id.register_email1);
+        register_password1 = (EditText) findViewById(R.id.register_password1);
+        delete_data = findViewById(R.id.data_delete);
+        data_search = findViewById(R.id.data_search);
+        btnViewshow = findViewById(R.id.btnshow);
+
+        db = openOrCreateDatabase("StudentDB", Context.MODE_PRIVATE, null);
+        db.execSQL("CREATE TABLE IF NOT EXISTS student(name VARCHAR,email VARCHAR,password VARCHAR);");
+        btnAdd2 =findViewById(R.id.btnAdd2);
+        btnAdd2.setOnClickListener(this);
+        btnViewshow.setOnClickListener(this);
+
+
+    }
+
+    @Override
+    public void onClick(View view) {
+
+        if (view == delete_data) {
+            // Checking empty roll number

+            if (register_email1.getText().toString().trim().length() == 0) {
+                showMessage("Error", "Please enter Rollno");
+                return;
+            }
+            // Searching roll number

+            Cursor c = db.rawQuery("SELECT * FROM student WHERE email='" + register_email1.getText() + "'", null);
+            if (c.moveToFirst()) {
+                // Deleting record if found

+                showMessage("Success", "Record Deleted");
+                db.execSQL("DELETE FROM student WHERE email='" + register_email1.getText() + "'");
+            } else {
+                showMessage("Error", "Invalid email");
+            }
+            clearText();
+        }
+        // Modifying a record

+
+        // Viewing a record

+        if (view == data_search) {
+            // Checking empty roll number

+            if (register_email1.getText().toString().trim().length() == 0) {
+                showMessage("Error", "Please enter Rollno");
+                return;
+            }
+            // Searching roll number

+            Cursor c = db.rawQuery("SELECT * FROM student WHERE email='" + register_email1.getText() + "'", null);
+            if (c.moveToFirst()) {
+                // Displaying record if found

+                register_password1.setText(c.getString(1));
+            } else {
+                showMessage("Error", "Invalid Rollno");
+                clearText();
+            }
+        }
+
+
+        if (view == btnAdd2) {
+            // Checking empty fields
+            if (register_name1.getText().toString().trim().length() == 0 || register_email1.getText().toString().trim().length() == 0 ||
+                    register_password1.getText().toString().trim().length() == 0) {
+                showMessage("Error", "Please enter all values");
+                return;
+            }
+            if(register_email1.getText().toString().matches(regex)) {
+                Cursor x = db.rawQuery("SELECT COUNT (email) FROM student WHERE email='" + register_email1.getText() + "'", null);
+                if (x.moveToFirst()) {
+                    if (x.getInt(0) == 0) {
+                        Toast.makeText(getApplicationContext(), "Pls wait patiently...while creating your account", Toast.LENGTH_LONG).show();
+                        db.execSQL("INSERT INTO student VALUES('" + register_name1.getText() + "','" + register_email1.getText() +
+                                "','" + register_password1.getText() + "');");
+                        Toast.makeText(getApplicationContext(), "Success....Account CREATED!!!!!", Toast.LENGTH_SHORT).show();
+                        clearText();
+                    } else {
+                        showMessage("email  already exists", "pls try a different one ");
+                        register_email1.setText("");
+                    }
+                } else {
+                    Toast.makeText(getApplicationContext(), "Password doesn't match...", Toast.LENGTH_LONG).show();
+                    register_password1.setText("");
+
+                }
+
+            }else{
+                showMessage("Error", "enter correct email ");
+            }
+
+        }
+        clearText();
+
+        // Deleting a record

+
+        // Viewing all records

+        if (view == btnViewshow) {
+            // Retrieving all records

+            Cursor c = db.rawQuery("SELECT * FROM student", null);
+            // Checking if no records found

+            if (c.getCount() == 0) {
+                showMessage("Error", "No records found");
+                return;
+            }
+            // Appending records to a string buffer

+            StringBuffer buffer = new StringBuffer();
+            while (c.moveToNext()) {
+                buffer.append("Name: " + c.getString(0) + "\n");
+                buffer.append("Email: " + c.getString(1) + "\n");
+                buffer.append("Password: " + c.getString(2) + "\n\n");
+            }
+            // Displaying all records

+            showMessage("Student Details", buffer.toString());
+        }
+        // Displaying info

+    }
+    public void showMessage(String title, String message){
+        AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        builder.setCancelable(true);
+        builder.setTitle(title);
+        builder.setMessage(message);
+        builder.show();
+    }
+    public void clearText(){
+
+        register_name1.setText("");
+        register_email1.setText("");
+        register_password1.setText("");
+        register_name1.requestFocus();
+    }
+
+
+}
+