//DatabaseHelper.java
package com.example.yourapp;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.*;
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "UserDB.db";
public static final String TABLE_NAME = "users";
public static final String COL_1 = "ID";
public static final String COL_2 = "USERNAME";
public static final String COL_3 = "PASSWORD";
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, USERNAME TEXT, PASSWORD TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
public boolean insertUser(String username, String password) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_2, username);
contentValues.put(COL_3, password);
long result = db.insert(TABLE_NAME, null, contentValues);
return result != -1;
}
public boolean checkUser(String username, String password) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_NAME + " WHERE USERNAME=? AND PASSWORD=?", new String[]{username, password});
return cursor.getCount() > 0;
}
public boolean userExists(String username) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_NAME + " WHERE USERNAME=?", new String[]{username});
return cursor.getCount() > 0;
}
}
//LoginActivity.java
package com.example.yourapp;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.*;
import androidx.appcompat.app.AppCompatActivity;
public class LoginActivity extends AppCompatActivity {
EditText username, password;
Button loginBtn, signupRedirectBtn;
DatabaseHelper db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
username = findViewById(R.id.etUsername);
password = findViewById(R.id.etPassword);
loginBtn = findViewById(R.id.btnLogin);
signupRedirectBtn = findViewById(R.id.btnSignupRedirect);
db = new DatabaseHelper(this);
loginBtn.setOnClickListener(v -> {
String user = username.getText().toString();
String pass = password.getText().toString();
if (db.checkUser(user, pass)) {
Toast.makeText(LoginActivity.this, "Login Successful", Toast.LENGTH_SHORT).show();
startActivity(new Intent(LoginActivity.this, MainActivity.class));
finish();
} else {
Toast.makeText(LoginActivity.this, "Invalid credentials", Toast.LENGTH_SHORT).show();
}
});
signupRedirectBtn.setOnClickListener(v -> startActivity(new Intent(LoginActivity.this, SignupActivity.class)));
}
}
//SignupActivity
package com.example.yourapp;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.*;
import androidx.appcompat.app.AppCompatActivity;
public class SignupActivity extends AppCompatActivity {
EditText username, password, confirmPassword;
Button signupBtn;
DatabaseHelper db;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_signup);
username = findViewById(R.id.etUsernameSignup);
password = findViewById(R.id.etPasswordSignup);
confirmPassword = findViewById(R.id.etConfirmPassword);
signupBtn = findViewById(R.id.btnSignup);
db = new DatabaseHelper(this);
signupBtn.setOnClickListener(v -> {
String user = username.getText().toString();
String pass = password.getText().toString();
String cpass = confirmPassword.getText().toString();
if (user.equals("") || pass.equals("") || cpass.equals("")) {
Toast.makeText(SignupActivity.this, "All fields are required", Toast.LENGTH_SHORT).show();
} else if (!pass.equals(cpass)) {
Toast.makeText(SignupActivity.this, "Passwords do not match", Toast.LENGTH_SHORT).show();
} else if (db.userExists(user)) {
Toast.makeText(SignupActivity.this, "User already exists", Toast.LENGTH_SHORT).show();
} else {
if (db.insertUser(user, pass)) {
Toast.makeText(SignupActivity.this, "Signup Successful", Toast.LENGTH_SHORT).show();
startActivity(new Intent(SignupActivity.this, LoginActivity.class));
finish();
} else {
Toast.makeText(SignupActivity.this, "Signup Failed", Toast.LENGTH_SHORT).show();
}
}
});
}
}
//activity_login.xml
<?xml version="1.0" encoding="utf-8"?>
<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="24dp"
android:gravity="center">
<EditText
android:id="@+id/etUsername"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Username" />
<EditText
android:id="@+id/etPassword"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Password"
android:inputType="textPassword" />
<Button
android:id="@+id/btnLogin"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Login" />
<Button
android:id="@+id/btnSignupRedirect"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="No account? Sign up" />
</LinearLayout>
//activity_signup.xml
<?xml version="1.0" encoding="utf-8"?>
<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="24dp"
android:gravity="center">
<EditText
android:id="@+id/etUsernameSignup"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Username" />
<EditText
android:id="@+id/etPasswordSignup"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Password"
android:inputType="textPassword" />
<EditText
android:id="@+id/etConfirmPassword"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Confirm Password"
android:inputType="textPassword" />
<Button
android:id="@+id/btnSignup"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Sign Up" />
</LinearLayout>
Steps to Integrate Login/Signup
🔹 1. Add Activities to AndroidManifest.xml
Open AndroidManifest.xml and add:
<application ... >
<activity android:name=".MainActivity" />
<activity android:name=".SignupActivity" />
<activity android:name=".LoginActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
This makes LoginActivity the first screen when the app launches.
- Connect to Your Main App Screen
Let’s say your main screen is MainActivity.java, already existing. In LoginActivity.java, modify this part:
if (db.checkUser(user, pass)) {
Toast.makeText(LoginActivity.this, "Login Successful", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
intent.putExtra("username", user); // optional
startActivity(intent);
finish(); // prevent back navigation to login
}
- Access the Logged-in User in MainActivity (Optional)
In MainActivity.java, you can get the logged-in username:
String username = getIntent().getStringExtra("username");
TextView welcome = findViewById(R.id.tvWelcome);
welcome.setText("Welcome, " + username + "!");
- (Optional) Add a Logout Button in MainActivity
To go back to login screen:
Button logoutBtn = findViewById(R.id.btnLogout);
logoutBtn.setOnClickListener(v -> {
Intent intent = new Intent(MainActivity.this, LoginActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); // clear back stack
startActivity(intent);
});
Add the DatabaseHelper.java to Your java Folder
Just right-click your java package, choose New > Java Class, name it DatabaseHelper, and paste the provided code.Add XML Layouts
Copy:
activity_login.xml → res/layout/activity_login.xml
activity_signup.xml → res/layout/activity_signup.xml
Use the layout editor or just paste the XML directly.