I’m working on a Android Studio app using Java. I started working on the database today (SQLite Database) and I’ve created the myDatabaseHelper class.

package com.example.findyourworker;

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

import androidx.annotation.Nullable;

class MyDatabaseHelper extends SQLiteOpenHelper {
    private Context context;
    private static final String DATABASE_NAME = "accounts.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_NAME = "users_data";
    private static final String COLUMN_ID = "_id";
    private static final String COLUMN_USERNAME = "username";
    private static final String COLUMN_PASSWORD = "password";
    private static final String COLUMN_EMAIL = "email";
    public MyDatabaseHelper(@Nullable Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.context = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String query ="CREATE TABLE " + TABLE_NAME +
                " (" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                COLUMN_USERNAME + " TEXT, " +
                COLUMN_PASSWORD + " TEXT, " +
                COLUMN_EMAIL + " TEXT);";
        db.execSQL(query);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }

    void addAccount(String username,String password,String email) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put(COLUMN_USERNAME, username);
        cv.put(COLUMN_PASSWORD, password);
        cv.put(COLUMN_EMAIL, email);
        long result = db.insert(TABLE_NAME, null, cv);
        if (result == -1) {
            Toast.makeText(context, "Failed", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(context, "Added Successfully", Toast.LENGTH_SHORT).show();
        }
    }

    boolean checkLogin(String email, String password) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {COLUMN_ID};
        String selection = COLUMN_EMAIL + "=? AND " + COLUMN_PASSWORD + "=?";
        String[] selectionArgs = {email, password};
        Cursor cursor = db.query(TABLE_NAME, columns, selection, selectionArgs, null, null, null);
        boolean loginSuccessful = cursor != null && cursor.getCount() > 0;
        if (cursor != null) {
            cursor.close();
        }
        return loginSuccessful;
    }

    boolean checkUsernameExists(String username) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {COLUMN_ID};
        String selection = COLUMN_USERNAME + "=?";
        String[] selectionArgs = {username};
        Cursor cursor = db.query(TABLE_NAME, columns, selection, selectionArgs, null, null, null);
        boolean usernameExists = cursor != null && cursor.getCount() > 0;
        if (cursor != null) {
            cursor.close();
        }
        return usernameExists;
    }

    boolean checkPasswordExists(String password) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {COLUMN_ID};
        String selection = COLUMN_PASSWORD + "=?";
        String[] selectionArgs = {password};
        Cursor cursor = db.query(TABLE_NAME, columns, selection, selectionArgs, null, null, null);
        boolean passwordExists = cursor != null && cursor.getCount() > 0;
        if (cursor != null) {
            cursor.close();
        }
        return passwordExists;
    }

    boolean checkEmailExists(String email) {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] columns = {COLUMN_ID};
        String selection = COLUMN_EMAIL + "=?";
        String[] selectionArgs = {email};
        Cursor cursor = db.query(TABLE_NAME, columns, selection, selectionArgs, null, null, null);
        boolean emailExists = cursor != null && cursor.getCount() > 0;
        if (cursor != null) {
            cursor.close();
        }
        return emailExists;
    }
}

And this is how I implemented the use of this DATABASE in the register page:

submit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // Inside onClick, update variables based on input validation
                username = un.getText().toString();
                password = pass.getText().toString();
                email = em.getText().toString();

                unValid = !TextUtils.isEmpty(username) && isUsernameValid(username);
                passValid = !TextUtils.isEmpty(password) && isValidPassword(password);
                emailValid = !TextUtils.isEmpty(email) && isValidEmail(email);

                if (unValid && passValid && emailValid) {
                    // All fields are valid, proceed with the signup process
                    if (!myDB.checkUsernameExists(username) && !myDB.checkEmailExists(email)) {
                        myDB.addAccount(username.trim(), password.trim(), email.trim());
                        Intent intent = new Intent(signup.this, fragments_host.class);
                        // startActivity(intent);
                    } else {
                        if (myDB.checkEmailExists(email) && myDB.checkUsernameExists(username)) {
                            Toast.makeText(context, "Email and Username Already Exist", Toast.LENGTH_SHORT).show();
                        } else if (myDB.checkUsernameExists(username)) {
                            Toast.makeText(context, "Username Already Exists", Toast.LENGTH_SHORT).show();
                        } else if (myDB.checkEmailExists(email)) {
                            Toast.makeText(context, "Email Already Exists", Toast.LENGTH_SHORT).show();
                        }
                    }
                } else {
                    // Handle invalid input fields here
                    if (!unValid) {
                        un.setTextColor(Color.RED);
                        vibrateDevice(signup.this, 200);
                        new Handler().postDelayed(() -> un.setTextColor(Color.BLACK), 200);
                    }
                    if (!passValid) {
                        pass.setTextColor(Color.RED);
                        vibrateDevice(signup.this, 200);
                        new Handler().postDelayed(() -> pass.setTextColor(Color.BLACK), 200);
                    }
                    if (!emailValid) {
                        em.setTextColor(Color.RED);
                        vibrateDevice(signup.this, 200);
                        new Handler().postDelayed(() -> em.setTextColor(Color.BLACK), 200);
                    }
                }
            }
        });

And in the register it works. My problem is with the login page:

submit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (myDB.checkEmailExists(email) && myDB.checkPasswordExists(password)) {
                    Toast.makeText(context, "Login was Successful.", Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(login.this, fragments_host.class);
                    startActivity(intent);
                } else {
                    Toast.makeText(context, "Account doesn't exist.", Toast.LENGTH_SHORT).show();
                }
            }
        });

If anyone has any idea why the login page database connection is not working please leave a comment or an answer your help would be much appreciated!

I tried running pieces of the code by ChatGPT and everything looks correct. And I tried modifying the code a little and nothing worked. I also tried to locate the DATABASE and watch it live and I couldn’t find it in the folders of my project.