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MainActivity.java

+package com.example.fund_restart;
+
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+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 MainActivity extends AppCompatActivity implements View.OnClickListener {
+    EditText email,password;
+    Button loginbutton;
+    TextView register,logintext,admin_login;
+    SQLiteDatabase d;
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        logintext = findViewById(R.id.logintext);
+        email = (EditText) findViewById(R.id.username);
+        password = (EditText) findViewById(R.id.password);
+        admin_login = findViewById(R.id.adminlog);
+        register = findViewById(R.id.register);
+        register.setOnClickListener(this);
+        logintext.setOnClickListener(this);
+        admin_login.setOnClickListener(this);
+       d = openOrCreateDatabase("StudentDB", Context.MODE_PRIVATE, null);
+    }
+
+    @Override
+    public void onClick(View v) {
+        if(v.getId() == R.id.adminlog){
+            Intent admin = new Intent(this,Adminpre.class);
+            startActivity(admin);
+        }
+        if(v.getId() == R.id.register){
+            Intent register_intent = new Intent(this,Register.class);
+            startActivity(register_intent);
+        }
+        if(v.getId() == R.id.logintext){
+
+            if(email.getText().toString().isEmpty() || password.getText().toString().isEmpty()) {
+                {
+                    AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);
+                    alertDialog.setTitle("Alert");
+                    alertDialog.setMessage("Fill all the details");
+                    alertDialog.setPositiveButton("ok", new DialogInterface.OnClickListener() {
+                        @Override
+                        public void onClick(DialogInterface dialog, int which) {
+
+                        }
+                    });
+                    alertDialog.show();
+                }}
+            else
+            {
+                Cursor cus=d.rawQuery("SELECT count(email) FROM student WHERE email ='" + email.getText() + "'", null);
+                if(cus.moveToFirst())
+                {
+                    if(cus.getInt(0)>=1)
+                    {
+                        Cursor cu = d.rawQuery("SELECT password FROM student WHERE email='" + email.getText() + "'", null);
+                        if (cu.moveToFirst()) {
+                            // Displaying record if found

+                            if (cu.getString(0).equals(password.getText().toString()) ) {
+                                Toast.makeText(getApplicationContext(), "Logging in....", Toast.LENGTH_SHORT).show();
+                                Intent x = new Intent(MainActivity.this, Login.class);
+                                startActivity(x);
+                            }
+
+                            else {
+                                showMessage("Error", "Invalid password");
+                                password.setText("");
+                            }
+                        }
+                        cu.close();
+                    }
+                    else if(cus.getInt(0)==0)
+                    {
+                        showMessage("Create an account first", "No account found in this name");
+                    }
+                }
+                cus.close();}
+
+        }
+    }
+
+    private void showMessage(String error, String invalid_password) {
+        AlertDialog.Builder builder = new AlertDialog.Builder(this);
+        builder.setCancelable(true);
+        builder.setTitle(error);
+        builder.setMessage(invalid_password);
+        builder.show();
+    }
+}